72 Duster Resurrection

[moparmat2000]

Option 2 is replace only absolutely what it needs to make it work and stop if you intend to rip it all out in a year or less to install a disc brake setup and dont want to waste the money on the drums.

I'd go with option 1 and make it safe to drive for a number of years. This way you can concentrate on everything else it needs and not have to worry about the brakes. Your biggest single expense is going to be $49 for a 9" manual drum brake master cylinder, everything else is nickel & dime stuff.

If you plan on going big bolt pattern way later, why not paint up the existing steel rims the car has now, put some not too expensive wider than stock black wall radials on them, and add dog dish caps, and maybe some trim or beauty rings, or leave em open with chrome acorn lug nuts. These looks usually work pretty good if you paint the rims black. These are inexpensive wheel treatments to do and look good.

Please show some pix of the condition of the rest of the car

 

[Duster Captain]

The good thing is the lines are clear with no blockages. You need to do the rears the same way Wheel cylinders are cheap. At least on rock auto for some reason i think the RH one is.

Theres several ways to go on this one. If the left one bleeds fine and doesnt leak, you may want to concider leaving that one alone if its not leaking, and just change the bad one, install new shoes etc, however if it leaks later on, you have ruined a set of new brake shoes.

If they are not going to be permanent because you will be eventually going discs in a few years, id go bare minimum you need to have it safe. Change the lines, wheel cylinders, master cylinder, and shoes. Get the drums turned on a brake lathe. Repack inner and outer wheel bearings on the front, and reuse the return springs that you have unless spring hardware kits are cheap enough. With the new shoes set to the correct drag initially with the brake spoon , this setup would be ok to safely stop a stock 318.

Rockauto will help you keep it cheap.

Drum brake parts are cheap on rock auto. The key word is closeout, and try to get everything shipped from the same location to save on shipping.

Wagner #2330 front $5.57 closeout
Wagner #2329 rear $5.57 closeout

Carlson H7130 spring hardware kit $4.44 closeout (same kit fits front and rear 9"drums)

Front wheel seals National 41257 $0.64 each

Raybestos C washer 2 reqd W6477 $0.02

Etc etc by the time the smoke clears with wheel cylinders brake hoses, and master cylinder, your prob going to be into it $75 - $85. But it will be safe to drive, and you can use that brake system for 5 -7 years as a daily driver with a /6 or a stock 2bbl 318 , while doing any other stuff it needs and building up the funds and parts to do a disc conversion and a more powerful V8

Option 2 is replace only absolutely what it needs to make it work and stop if you intend to rip it all out in a year or less to install a disc brake setup and dont want to waste the money on the drums.

I'd go with option 1 and make it safe to drive for a number of years. This way you can concentrate on everything else it needs and not have to worry about the brakes. Your biggest single expense is going to be $49 for a 9" manual drum brake master cylinder, everything else is nickel & dime stuff.

If you plan on going big bolt pattern way later, why not paint up the existing steel rims the car has now, put some not too expensive wider than stock black wall radials on them, and add dog dish caps, and maybe some trim or beauty rings, or leave em open with chrome acorn lug nuts. These looks usually work pretty good if you paint the rims black. These are inexpensive wheel treatments to do and look good.

Please show some pix of the condition of the rest of the car

Thanks for all the good info, I think rebuilding the entire drum break system to safe reliable status is what I'm going to do. I plan on driving for at while until I go to disk brakes and v8. The 318 I have will be a good bit over stock when it's ready, but that's a topic for later...

I like the suggestion about the tires. I think painting the rims, wide rubber, and some shiny hardware would look killer and hopefully be pretty cheap to do.

I somehow managed to have a mostly free Saturday tomorrow, so I will be working on the duster. I will take some more pics of the rest of the car then. It's in pretty good shape all around as far as I can see.

 

[trapster]

Did they ever put 10 inch drums on any slant 6 A body ?

 

[Charrlie_S]

Did they ever put 10 inch drums on any slant 6 A body ?

Yes. I'm not sure what year they started, but they were an option, at least from 1965 up, if not standard.

 

[moparmat2000]

Back in 1970/1971 plymouth offered a duster twister. It was essentially a slant 6 or a 318 with a 340 duster exterior dress up package. It came with a blacked out hood, 340 stripes on the sides without 340 callouts, tallight panel black outs with duster twister callout, small bolt pattern rallye wheels, color keyed dual sport mirrors, non functional twin scoop hood , and a sharktooth 340 grille.

You could probably duplicate this with not too much effort. The sharktooth grille would be the expensive part. Those go for $1,000 or more. You could prob just use your stocker and black it out or do it in a dark argent silver.

I have a set of 6 small bolt pattern rallyes they are 14x 5.5 for sale in the brakes and wheels section. They come with 5 center caps, and no beauty rings, though i dont think the twisters came with rings. Just the rims and caps. These would be great to have. 4 on the car, one for a matching spare in the trunk, and 1 for a spare rim just in case one gets damaged. I have had them for sale, and 2 of them are on my sons 69 cuda. I would need 2 stock steel rims back with tires as i need them to keep the car rollable. Tires can be dryrotted, and shot, as long as they hold air. Would prefer a pair of 15x7 fifth ave steel BBP rims to keep it rollable for the disc brake conversion i plan on doing.

Heres twister pix

 

[moparmat2000]

Also, to keep from driving you nuts, quite literally if you have not figured it out yet, mopar used left hand threaded lug nuts on the left side of the car and Right hand threaded lug nuts on the right side of the car, at least up to 1972. If you look at the center of the stud it will be stamped either with an R or an L indicating the thread direction. I would recommend knocking out the LH threaded studs and making them all RH. Unless somebody in the past has already done so. Replacement RH studs are cheap. Rock auto has the 7/16" rears on closeout for $0.51 each, and fronts on closeout for $0.56 each. Installation is easy too. Just slip em in from the back, stack up a bunch of loose fitting washers on the stud from the front, and install the lug nut, then tighten the lug nut to pull the stud in. I use an impact gun with my air compressor to pull em in.

 

[moparmat2000]

Heres pix of the SBP 14" rallyes i have. As you can see i have 2 mounted on the 69 notchback. It is a long term project i am collecting parts up for. I was going to temp install the M body brakes on the front to keep it a roller. Thats where the 5th ave wheels would come in, and switch the other steelies to the back. Eventually i will be getting a ford xploder sport trak rear for the back, and chucking the 7.25 pegleg under the back.

 

[Duster Captain]

I'm out and about right now, so I will need to read through your last posts when I get home but I have a situation I would like some input on.

I found a Mopar Guy in town who is going to sell me all this stuff off a 74 duster (e body?) For $250:

Disk rotors
Spindles
Calipers
Upper and lower control arms
2 14" bbp rims

Sounds like a good deal but will this all for into my 72 duster? I know I might need to do the ball joint adapter for the uppers.

Any other concerns?

 

[Duster Captain]

This is the stuff I could get for $250

 

[moparmat2000]

Thats a screaming good deal on an A body disc setup. Local too. A 74 duster is still an A body like yours His upper control arms are the big ball joint ones. Thats what you use with those disc spindles with no adaptor sleeves. You will need a ball joint for the one upper control arm thats painted. Its a K772 joint. As well as bushings for it. Might as well rebuild both of them with new joints and bushings if your going to use them. Or you can use the small ball joint ones on your car with the adaptor sleeves

The lower control arms are the same part from 1962 to 1976. Only difference is some have tabs welded on them for swaybars. The ones on your car will work for this swap.

You will need the A body disc brake hoses from 74 to 76, disc brake proportioning valve for A body from 74 to 76, and the manual brake A body disc brake master cylinder from 74 to 76, and ten 1/2" RH lug nuts since the pic shows there arent any.

If you decide to use your small joint arms with the doctor diff adaptor sleeves, and original lower control arms, you can sell the big joint arms, and those nice painted lower control arms and recoup some of your money. Id look on fabo sales and see what the going rate is on those pieces before selling them, as well as selling all the front drum brake stuff.

The bonus is the big bolt pattern 14" wheels. And extra parts that come with it. Typically just the brake setup from the spindle out, with no extras like rims and suspension arms goes for $250-$300. You will notice the disc brakes come with way bigger studs 1/2" instead on the 7/16" ones on your drums.

If you buy this setup, and i recommend you do since its local, and you can recoup your money on the extras you dont need, unless you want to wait and come out this way for a set of cheaper M body brakes (same thing except for larger piston caliper, slightly changed spindle) you can prob go 2 ways.

1 sink a bunch of money in the disc brake setup right away and swap it in,

2 do a quickie fix on the drum setup with minimal money spent just so you can get the car up and running, and round up all the parts including new upper and lower ball joints, pads, master cylinder etc and rebuild the disc brakes as time and money allow and get it all ready, so you can do the disc swap in a weekend.

 

[Duster Captain]

Thats a screaming good deal. Local too. A 74 duster is still an A body like yours His upper control arms are the big ball joint ones. Thats what you use with those disc spindles with no adaptorr sleeves. You will need a ball joint for the one upper control arm thats painted. Its a K772 joint. As well as bushings for it. Might as well rebuild both of them with new joints and bushings if your going to use them. Or you can use the small ball joint ones on your car with the adaptor sleeves

The lower control arms are the same part from 1962 to 1976. Only difference is some have tabs welded on them for swaybars. The ones on your car will work for this swap.

You will need the A body disc brake hoses from 74 to 76, disc brake proportioning valve for A body from 74 to 76, and the manual brake A body disc brake master cylinder from 74 to 76.

If you decide to use your small joint arms with the adaptor sleeves, and original lower control arms, you can sell the big joint arms, and those nice painted lower control arms and recoup some of your money. Id look on fabo sales and see what the going rate is on those pieces before selling them.

The bonus is the big bolt pattern wheels. You will notice the disc brakes come with way bigger studs 1/2" instead on the 7/16" ones on your drums.

Awesome, that's what I was hoping! Thanks! I'll driving over to get the parts now, I'll post some more updates when I'm back home. I know I owe ya'll some pics of the rest of the car.

Also, I did not know about the right hand, left hand lug nut thing, but I took all my front lugs of normally (right hand) so someone just have swapped them already...

 

[moparmat2000]

I snapped 2 lugs off on my 68 charger back in 1985 when i was 15 years old because i didnt know. My dad showed me the L and R. The rest spun right off when i reversed the impact gun, my dad and i changed every one of em to RH that afternoon.

 

[moparmat2000]

If you like the no nonsense street race look of black steel wheels and chrome lugnuts, those wheels he's got are 14x5.5. Perfect for the front. If/when you upgrade the rear to the same big bolt pattern, find some 15x7 M body steelies for the back. Give em the same paint and lugnut treatment. Put you some 205-70R14s on the front, and some 255-60R15s on the rear. Car will look bad ***.

 

[moparmat2000]

Also i mentioned the upper and lower ball joints and upper control arm bushings only because if your that far in you might as well replace them while your at it. Avoid at all costs the evilbay complete front end kits for $80. You get what you pay for with those. I hear moog is no good anymore too since they are made in china too. Theres 2 online places that package and sell complete front end kits with high quality parts. PST (performance suspension technology) and just suspensions.

Since your putting 74 disc brakes on a 72, you will need to talk with them directly to get all the correct parts in your kit. For example

You decide to use your small joint upper arms with the adaptor sleeves, and put the 74 up disc brakes on, you will need the 1972 kit, with 1974 disc brake lower ball joints.

If you decide to use the large joint upper arms with the 74 up disc brakes on your 72, you will need the 1972 kit with 1974 large flat rate box upper ball joints and 1974 disc brake lower ball joints.

 

[Duster Captain]

Back in 1970/1971 plymouth offered a duster twister. It was essentially a slant 6 or a 318 with a 340 duster exterior dress up package. It came with a blacked out hood, 340 stripes on the sides without 340 callouts, tallight panel black outs with duster twister callout, small bolt pattern rallye wheels, color keyed dual sport mirrors, non functional twin scoop hood , and a sharktooth 340 grille.

You could probably duplicate this with not too much effort. The sharktooth grille would be the expensive part. Those go for $1,000 or more. You could prob just use your stocker and black it out or do it in a dark argent silver.

I have a set of 6 small bolt pattern rallyes they are 14x 5.5 for sale in the brakes and wheels section. They come with 5 center caps, and no beauty rings, though i dont think the twisters came with rings. Just the rims and caps. These would be great to have. 4 on the car, one for a matching spare in the trunk, and 1 for a spare rim just in case one gets damaged. I have had them for sale, and 2 of them are on my sons 69 cuda. I would need 2 stock steel rims back with tires as i need them to keep the car rollable. Tires can be dryrotted, and shot, as long as they hold air. Would prefer a pair of 15x7 fifth ave steel BBP rims to keep it rollable for the disc brake conversion i plan on doing.

Heres twister pix

View attachment 1715094065

View attachment 1715094066

View attachment 1715094067

Love the look of that twister, that will be something to consider when it comes time for paint/body! Hopefully I wont need the small bolt pattern wheels anymore after buying the 2 bbp wheels, but thanks.

Thats a screaming good deal on an A body disc setup. Local too. A 74 duster is still an A body like yours His upper control arms are the big ball joint ones. Thats what you use with those disc spindles with no adaptor sleeves. You will need a ball joint for the one upper control arm thats painted. Its a K772 joint. As well as bushings for it. Might as well rebuild both of them with new joints and bushings if your going to use them. Or you can use the small ball joint ones on your car with the adaptor sleeves

The lower control arms are the same part from 1962 to 1976. Only difference is some have tabs welded on them for swaybars. The ones on your car will work for this swap.

You will need the A body disc brake hoses from 74 to 76, disc brake proportioning valve for A body from 74 to 76, and the manual brake A body disc brake master cylinder from 74 to 76, and ten 1/2" RH lug nuts since the pic shows there arent any.

If you decide to use your small joint arms with the doctor diff adaptor sleeves, and original lower control arms, you can sell the big joint arms, and those nice painted lower control arms and recoup some of your money. Id look on fabo sales and see what the going rate is on those pieces before selling them, as well as selling all the front drum brake stuff.

The bonus is the big bolt pattern 14" wheels. And extra parts that come with it. Typically just the brake setup from the spindle out, with no extras like rims and suspension arms goes for $250-$300. You will notice the disc brakes come with way bigger studs 1/2" instead on the 7/16" ones on your drums.

If you buy this setup, and i recommend you do since its local, and you can recoup your money on the extras you dont need, unless you want to wait and come out this way for a set of cheaper M body brakes (same thing except for larger piston caliper, slightly changed spindle) you can prob go 2 ways.

1 sink a bunch of money in the disc brake setup right away and swap it in,

2 do a quickie fix on the drum setup with minimal money spent just so you can get the car up and running, and round up all the parts including new upper and lower ball joints, pads, master cylinder etc and rebuild the disc brakes as time and money allow and get it all ready, so you can do the disc swap in a weekend.

Yep, that was too good of a deal, so I went and picked it all up for $250, see more pics below.

I think I might go ahead and do option 1 here depending on what the shopping list total is. I should just bite the bullet now and be completely v8 ready and safer on the road. Are the bigger ball joints "stronger" for going to a heavier v8?

I plan on building the front end the best I can afford and then selling all unused parts that are leftover for sure.

I snapped 2 lugs off on my 68 charger back in 1985 when i was 15 years old because i didnt know. My dad showed me the L and R. The rest spun right off when i reversed the impact gun, my dad and i changed every one of em to RH that afternoon.

Bummer, guess you gotta learn the hard way sometimes, I would have done the same thing if mine had not been switched to RH in the past.

If you like the no nonsense street race look of black steel wheels and chrome lugnuts, those wheels he's got are 14x5.5. Perfect for the front. If/when you upgrade the rear to the same big bolt pattern, find some 15x7 M body steelies for the back. Give em the same paint and lugnut treatment. Put you some 205-70R14s on the front, and some 255-60R15s on the rear. Car will look bad ***.

Love it, sounds slick. Probably keep the rear end tires the same for now unless I can find another local deal that is cheap for upgrades...then yes, up to the bbp wheels

Also i mentioned the upper and lower ball joints and upper control arm bushings only because if your that far in you might as well replace them while your at it. Avoid at all costs the evilbay complete front end kits for $80. You get what you pay for with those. I hear moog is no good anymore too since they are made in china too. Theres 2 online places that package and sell complete front end kits with high quality parts. PST (performance suspension technology) and just suspensions.

Since your putting 74 disc brakes on a 72, you will need to talk with them directly to get all the correct parts in your kit. For example

You decide to use your small joint upper arms with the adaptor sleeves, and put the 74 up disc brakes on, you will need the 1972 kit, with 1974 disc brake lower ball joints.

If you decide to use the large joint upper arms with the 74 up disc brakes on your 72, you will need the 1972 kit with 1974 large flat rate box upper ball joints and 1974 disc brake lower ball joints.

Definitely going to rebuild the whole front end while I am here at a pace I can afford. I have to get some things fixed up with the engine anyways.

Thanks for the heads up on the rebuild kits, I will check out the companies you recommend and be sure to get the right mix of 72 and 74 parts depending on how I go with the control arms.

Actually, when I figure out which way I want to go, can I post my shopping list so you can see if I missed anything? That would be very helpful.

Finally, as promised, various pics of the rest of the car and some comments:

Can anyone tell me what kind of rear end I have from this?

Some rust in wheel area as usual...

Fresh new jack stands always add a bit of class to a brake job. Am I going to be yelled at for how I have this jacked up? I know I will need to get off that lower control arm to do the brake/suspension upgrade.

A little hood rust but nothing scary

So I have run the engine for about 10 mins total and driven maybe 50 yards down the street. Does this gunk look like trouble? I'm not sure if it was like that when I got it and we spilled all kinds of stuff (cleaner, gas, etc) when we were working on the engine, so im not sure what it all is....does not look sever to me, but...

The captain abides.

 

[moparmat2000]

Underneath, yep normal 40 years of slime.

Upgrade to the big ball joint because you have the arms, and they are a little stronger, but also because the cost for the ball joints is the same BBJ or SBJ , if you go SBJ then you got to spend $45 for adaptor sleeves. After the cost of the sleeves is figured in, if you sell the BBJ arms you might make $50 on em if they are worth $100, prob not worth it. I sold a set of SBJ arms for $30, and kept the BBJ arms for my use.

I think the sleeves are for guys that dont have the BBJ arms but have the brakes. Or you could use the sleeves, and SBJ arms, and sell the BBJ arms. I dunno what the going price is for those lately.

Rear axle, measure the bolt circle. Somebody else put wheels and a grant gt steering wheel on it. Its a possibility the rear ends been changed out. If its got a 3" axle tube, and the BBP axles its prob an 8.25" rear. Thats a good one. You need to keep it. The 8.25" or 8&1/4" as some call it can handle V8 power well up to 400hp after that its a toss up.

The good thing about the 8.25" is that rear end gears and a sure grip locker (positrac)out of jeep grand cherokees, and dodge dakotas fit it.

Check the tube diameter, as you can still have the BBP axle setup in the weaker 7.25" rear end. I had a 74 dart parts car that had a 7.25, and had BBP axles under it. When it comes to Ma Mopar anything was possible lol.

 

[moparmat2000]

That rust is nothing. I mean its got to be taken care of eventually or it will get worse, however its nothing compared to what some guys on this site deal with.

Before you dissassemble the suspension on the front, you will have to drop the tension on the torsion bars first.

Theres a few other things you need to do in regards to the lower control arms on dissassembly to make your life easier getting it apart, and on reassembly so the lower arms dont rip the bushings first time the suspension deflects up and down.

I will send you a PM

 

[moparmat2000]

Torsion bar adjustor bolts are here in the lower arms, you have to loosen them all the way to drop the tension off the torsion bars. Then take the suspension apart. Even if doing just the brake swap you have to do this.

Set jackstands under framerails where they go from angled to flat under front floorpans. Not under rocker panels, the cars weight will damage them.

 

[Duster Captain]

Sorry for going silent, been a busy day. I will have some time to play tonight and tomorrow so I will be back on.

Appreciate the info as usual moparmat, I will give it a careful read through and add my comments/questions later today.

 

[trapster]

I would not get under the car with the jack and stands sitting on dirt. And I would also put the stands on the frame of the car. You don't want anything that can move or shift for any reason holding up the car.

 

[moparmat2000]

If you cant jack it up on pavement, i have seen guys use a wide piece of 3/4 plywood under the jack so spreads the load and it doesnt dig into the dirt. Under the jack stands you can put some 24x24 concrete pave blocks. You can get them at lowes or home depot pretty cheap in their outdoors area.

 

[killnine]

Never Never Never Never try to run a car or anything with bad gas in it. It could destroy the engine. what happens is it gums up the intake valves and they stick open when you stop the engine, the next time you start the pistons will hit the valves and unstick them, which is bad enough, but also you will most likely bend a bush rod when it drops out of the socket on the rocker, and additives to the fuel may help the issue, but then you may end up with a bunch of sediment in the carb.

and yes I know this from experience.

yep, next morning usually after it sits

 

[Duster Captain]

Underneath, yep normal 40 years of slime.

Upgrade to the big ball joint because you have the arms, and they are a little stronger, but also because the cost for the ball joints is the same BBJ or SBJ , if you go SBJ then you got to spend $45 for adaptor sleeves. After the cost of the sleeves is figured in, if you sell the BBJ arms you might make $50 on em if they are worth $100, prob not worth it. I sold a set of SBJ arms for $30, and kept the BBJ arms for my use.

I think the sleeves are for guys that dont have the BBJ arms but have the brakes. Or you could use the sleeves, and SBJ arms, and sell the BBJ arms. I dunno what the going price is for those lately.

Rear axle, measure the bolt circle. Somebody else put wheels and a grant gt steering wheel on it. Its a possibility the rear ends been changed out. If its got a 3" axle tube, and the BBP axles its prob an 8.25" rear. Thats a good one. You need to keep it. The 8.25" or 8&1/4" as some call it can handle V8 power well up to 400hp after that its a toss up.

The good thing about the 8.25" is that rear end gears and a sure grip locker (positrac)out of jeep grand cherokees, and dodge dakotas fit it.

Check the tube diameter, as you can still have the BBP axle setup in the weaker 7.25" rear end. I had a 74 dart parts car that had a 7.25, and had BBP axles under it. When it comes to Ma Mopar anything was possible lol.

Based on all that I think the right choice is to put the BBJ arms on. I want to make the best front end I can based on the parts I have and sell the leftovers.

So about the rear end, I dont have a set of calipers, shamefully, so I wrapped a piece of wire around the tube, then measured its length and got the diameter. My very rough tube diameter measurement is 2.6" in diameter. So is it just a 3" and my measurement was very rough or was there a two point something inch version?

I also have a pic of the diff:

And the tube:

The rear bolt pattern is this big:

So the back wheels are the 4" small bolt pattern right?

That rust is nothing. I mean its got to be taken care of eventually or it will get worse, however its nothing compared to what some guys on this site deal with.

Before you dissassemble the suspension on the front, you will have to drop the tension on the torsion bars first.

Theres a few other things you need to do in regards to the lower control arms on dissassembly to make your life easier getting it apart, and on reassembly so the lower arms dont rip the bushings first time the suspension deflects up and down.

I will send you a PM

Good to hear about the rust, it looks minimal to me too, just wanted another set of eyes on it. I plan on doing body/paint myself eventually...

I have heard about the torsion bar thing, I will read more into it and contact you if I need more advise, thanks.

Set jackstands under framerails where they go from angled to flat under front floorpans. Not under rocker panels, the cars weight will damage them.

I would not get under the car with the jack and stands sitting on dirt. And I would also put the stands on the frame of the car. You don't want anything that can move or shift for any reason holding up the car.

If you cant jack it up on pavement, i have seen guys use a wide piece of 3/4 plywood under the jack so spreads the load and it doesnt dig into the dirt. Under the jack stands you can put some 24x24 concrete pave blocks. You can get them at lowes or home depot pretty cheap in their outdoors area.

I would love to have a proper shop, If someone wants to sneak into my yard and build one I would take it! But unfortunately dirt is what I got.

I agree, I need to get some paving stones or similar. I have the jackstands on thick peices of solid wood boards so they dont sink, but its not ideal.

Also, so to be safe and have access to the from suspension, are you guys saying I should put the jack stands where my actual jack is in this pic?

 

[moparmat2000]

My shop is a pole barn. Cheapest way to build one if your city allows it. Poles are 4" square tube 3' deep cemented in. Then welded the framework to them and sheetmetaled it. I used the sheetmetal walls as a permanent concrete form, and only framed out for the roll up door, and people door.

Where the framerails go from angled down to flat, just a bit behind where your jack is at. Is good.

At the rear set them just fwd of the leafspring front eye on the flat of the rear framerail.

Your pic w the tape measure looks like 4.50" to me. So you prob already have a big bolt pattern rear axle. Try to bolt your small pattern front wheels on it. I bet they dont go. Another easy way to tell is try swapping the lug nuts. Small bolt pattern is 7/16" large bolt pattern is 1/2" your front lugs wont fit the rear, and the rear lugs will be swimming on the front studs.

Thats another good reason your doing the BBP disc swap. If the rear is already BBP, and front is SBP you gotta carry 2 different spares or you got a 50% chance of being screwed if you get a flat.

As i said, even the 7.25 could come as a BBP axle. The tube diameter and cover shape will determine if its a 7.25 or an 8.25. I will try to find and post a cover identification chart for you. I bet with your way of measuring, and getting 2.60" thats close enough to 2.50 that its prob a 7.25 rear. You can also measure the width of the U bolts at the spring plates. If its under 3" you have a 7.25" and still thats not bad. The brakes from the backing plate out from that will swap to an 8.25, and 8.75. So even if you redo the rear drums, you can move them to the better rear later, and you can get your wheels squared away where you only need 1 spare.

As said earlier if its an 8.25" its a keeper. Gears, and sure grips out of dakotas, and jeep grand cherokees with the 8.25 will fit. The jeep with a sure grip being way easier to find as it made it better for offroad, and with 3.55, 3.73, 3.90, and 4.10 ratios.

 

[barbee6043]

I have worked in dirt and jack stands sitting on a 2 x 8 too many times. I have a color bone that is noticeable out of "whack". don't ask HOW!!!! hint....and ( one time I can't blame a horse for my misfortune) ......please get a sheet of 5/8 or thicker plywood to work off and BE sure to chock the rear wheels so it can't go forward or backwards!!!! just be safe.