8 3/4" from a 1/2 Ton P/U or Van For "A" Body

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VIOLENT\6

VIOLENT\6

12 second N/A Slant 6?
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Everyone is saying how rare the 8 4/4" ousings are getting to be.

I live in a very rural area. Nearest medium sized city is 2 hiyrs drive. (Watertown to the west, Plattburg to the east)

Not a lot of old Mopar "B" bodies or the like around, but lots of pickup trucks in barnyards, etc.

I know there are 8 3/4" diffs used in those trucks. I had a '78 that had one.

Are they harder to narrow than units from a car?

Will standard "A" body axles work in those housings.

What about brake components?

Seems like the pumpkins would probably be the big pinion.
 
Their all the same amount of work to narrow. A-body axles will work if you use A-body brakes, which will bolt right up. The pinions aren't always the big ones. Lower powered trucks (slant 6's and 318's) often had the 741 case. It's still a very capable unit. Lots of guys running them in race cars turning 11's. I have a rear out of a 73 Van I'm narrowing for my Cuda right now.
 
The bonus is when you get into some of the earlier vehicles, 3.91 and sure grips were common. Used to look for the mid 60 to early 70 vans with slants. Usually geared numerically higher.
 
Even the axles are excellent to use.

Unlike the C body axles, they do not have the drop size step toward the end and you can pay to have them cut and resplined. You'll end up with large bolt pattern if you do, but a lot of people go that way for disc brake conversions anyway.

I know someone in Colorado who will cut and spline them for $75 a pair, so you can use the housing, axles and buy new flanges for your brakes and relocate the spring pirches.

I don't live in a rural area and I'm doing it on the '73 to save money.
 
My family has had 4 69-71 pickups.
All 741 case, 3.91 open gears, except one my dads 70 he bought new it had an optional 3.55 rear??????????
All four trucks were stick shift.
Dad said grandpa's long wheel base with 3.91 would get better milage than his short wheel base step side by 2 mpg.
Same motors 225 3 on the tree.
Maybe the step side be had something to do with areodynamics.
 
driving habits, dwell, gap and carb tune is likely to speculate those aspects.

3.91 gears on a heavy vehicle actually help improve fuel economy as well, in town.
 
I think only the 1/2 ton came with the 8 3/4. The 3/4 ton had the Dana.
 
DaveBonds said:
Even the axles are excellent to use.

Unlike the C body axles, they do not have the drop size step toward the end and you can pay to have them cut and resplined. You'll end up with large bolt pattern if you do, but a lot of people go that way for disc brake conversions anyway.

I know someone in Colorado who will cut and spline them for $75 a pair, so you can use the housing, axles and buy new flanges for your brakes and relocate the spring pirches.
Click to expand...


So, if I have the truck axles cut down & splined I will have the "big" bolt pattern.

Is that 5 X 4 1/2"?

I'm looking to swap OEM junk yard parts for disc brakes on the front so 4 X 4 1/2" would be great..
 
"I think only the 1/2 ton came with the 8 3/4. The 3/4 ton had the Dana."

I must respectfully disagree. Most 3/4-ton trucks and vans had the Chrysler 9-1/4" diff. Some 3/4-ton trucks may have had the Dana 60; I'm not sure. The 1-ton trucks generally had the Dana 70.
 
MOPARoldtimer said:
"I think only the 1/2 ton came with the 8 3/4. The 3/4 ton had the Dana."

I must respectfully disagree. Most 3/4-ton trucks and vans had the Chrysler 9-1/4" diff. Some 3/4-ton trucks may have had the Dana 60; I'm not sure. The 1-ton trucks generally had the Dana 70.
Click to expand...

Well whatever, my point was simply that the 3/4 ton did not come with the 8 3/4.
 
Measure the bolt pattern to make sure but I believe they were all 5 on 4-1/2".

There were a few 1/2 ton 4x4s made from 72-74 with a FIVE inch BP 8 3/4 housing. It's a bolt in swap for the 85-92 trucks if you want an 8 3/4. Other than that the 8 3/4 truck housings were 4 1/2 BP. Also note that trucks had the spring pads UNDER the leaf springs rather than on top of them, so they have to be relocated. The A-100 trucks and vans had the most narrow rears. The easiest non-a body 83/4 swap is still the 66-70 B body rear. here's a Mopar Muscle article on that:
http://www.moparmusclemagazine.com/...404_8_3_4_rear_axle_housing_swap/viewall.html
 
Yep, 66-70 work well with the 66-67 being the best choice. 68-70 are slightly wider.

That article is a victim of the rotten info regarding axle widths.
 
MOPARoldtimer said:
"I think only the 1/2 ton came with the 8 3/4. The 3/4 ton had the Dana."

I must respectfully disagree. Most 3/4-ton trucks and vans had the Chrysler 9-1/4" diff. Some 3/4-ton trucks may have had the Dana 60; I'm not sure. The 1-ton trucks generally had the Dana 70.
Click to expand...

RustyRatRod said:
Well whatever, my point was simply that the 3/4 ton did not come with the 8 3/4.
Click to expand...

Yes usually the 8.75 was not in 3/4 and 1T, the 9.25 replaced the 8.75 in the 1/2.

1T had 60's for a long time before 70's got under there, D-70's didn't get into and Dodge till 79, and weren't in the normal 1T, there was an option for the 60HD and 70 in the W-350, but most were regular D-60's and the 70's were used in the larger trucks.

.
 
Ill spill one of my not so well kept secrets here. If you find a mid-'70's 4x4 truck with an 8 3/4 rear under it, snag it. It will have a 3:55 Suregrip in it, as that was the only center that was compatible with the Dana 44 front axle, which would have a 3:54 ratio. Could you get lucky and find a 4:10 or 4:56 also?? Maybe, but I've never seen this in a mid 70's truck!!
 
Dana didn't supply D-70's to dodge till 79, someone could have put one in it over time, whats the bom # on the dana
 
If you had a 78 1/2 ton with an 8.75 in it , it was installed after it was new , Between my father an i we must have had a dozen dodge trucks , from the mid 70,s into the 90,s always 81/4.And the 4 wheel drive was given the 91/4 out back .I myself have only seen one 83/4 in a truck from 72 on , it was a 4x4 1974.
 
"Dana didn't supply D-70's to dodge till 79, someone could have put one in it over time, whats the bom # on the dana"

But how can that be true when even the 1977 FSM covers the Dana (then Spicer) 70 (see page 3-53 of the 1977 FSM)??

"The Dana 70 rear axle was first used in the Dodge W300 in 1958." - Wikipedia.

http://en.wikipedia.org/wiki/Dana_70

Perhaps you're reaching this conclusion because, prior to 1979, it was called the "Spicer 70" diff.??
 
kt340sport said:
If you had a 78 1/2 ton with an 8.75 in it , it was installed after it was new , Between my father an i we must have had a dozen dodge trucks , from the mid 70,s into the 90,s always 81/4.And the 4 wheel drive was given the 91/4 out back .I myself have only seen one 83/4 in a truck from 72 on , it was a 4x4 1974.
Click to expand...

I had a 78 1/2 ton 2WD stepside 4-speed & it had an 8 3/4 W/3.23 gears.
 
my dana 60 came out of a '81 1ton dodge B300 maxivan

had to get axles, endcaps and spring perches from Dr. Diff (Cass is his real name)

he told me to check the gears, since it was a van they were probably cherry

he was right... the gears inside were in perfect shape. the pickup truck axles take a lot more beating than the vans lol

the bom numbers are stamped on the axles (mine was 603994 1) ... you can look them up on the dana website http://www2.dana.com/expertforms/deabill.aspx

i also found a guy selling a powerlok (the good one from 67-69 mopars) on moparts, part number on the one i got was 25124x

whether you do an 8 3/4 or a dana you will pay the same for the axles / housing ends

www.doctordiff.com cass has all the stuff you would possibly need, he is the man
 
gregpurcell said:
The easiest non-a body 83/4 swap is still the 66-70 B body rear. here's a Mopar Muscle article on that:
http://www.moparmusclemagazine.com/...404_8_3_4_rear_axle_housing_swap/viewall.html
Click to expand...


crackedback said:
Yep, 66-70 work well with the 66-67 being the best choice. 68-70 are slightly wider.

That article is a victim of the rotten info regarding axle widths.
Click to expand...

I found a stripped "B" body housing today for $40. Nothing left on it but the studs & spring perchs..

It isn't even rusty. I has a nice even coat of faded black paint on it.

Is $40 a fair price?

It's supposed to be from a '69. I'll take my tapemeasure W/me when I go back to get it & do a thorough inspectioj & measure the width.
 
MOPARoldtimer said:
"Dana didn't supply D-70's to dodge till 79, someone could have put one in it over time, whats the bom # on the dana"

But how can that be true when even the 1977 FSM covers the Dana (then Spicer) 70 (see page 3-53 of the 1977 FSM)??

"The Dana 70 rear axle was first used in the Dodge W300 in 1958." - Wikipedia.

http://en.wikipedia.org/wiki/Dana_70

Perhaps you're reaching this conclusion because, prior to 1979, it was called the "Spicer 70" diff.??
Click to expand...

X2.

Here's pictures to back it up. The wheels aren't stock, but the axles/housings have never been swapped out.

1965 Fargo W300. Dana 70 front and rear.



1966 Dodge W300. Dana 70 front and rear.



1966 Dodge W500 (blue box). Dana 70 front and rear.



My W100 came with 8 3/4 rear, Dana 44 front. 4.10's.



 
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