8 3/4 help needed

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sdahmer

sdahmer

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Kind of a noob here so please bare with. 72 dart custom (4dr). So my local junkyard is having a half off sale this weekend so I wanted to go look for a 8 3/4 diff, currently have 7 1/4. What donor should I look for? Does it matter? I'm hoping on a sbp since that's what I currently have (new wheels and tires). Would converting a lbp to sbp be easy, in case I only find a lbp. Perches can be relocated if need be right? I know I'd need the u bolts and plates, is there anything else I should know? Thanks
 
Assuming they have any at all just familiarize yourself with what the cover and bolt pattern look like then happy hunting. Buy all you find. You can sell them here. If you find two for half, and sell one for full you will have a free rear. Keep your eyes open for the Dana's also.
 
I would buy new U bolts for the new installation. JMO. Do snag the plates. All you can find or can afford for that matter. If ya find BBP units i'm sure there are those that will gladly swap ya some SBP axels straight across. They should fit. I may be wrong and if so someone will come on and correct me. Be sure you score ya some SBP 8.75 drums if ya find a BBP diff and your wanting to stay with the small stuff. They can be drilled but it's a hassel. Remember, the punkin bolts up from the front on a mopar. The only other thing that will look close will be a ford 9" but you wont find that in a Mopar. It will say on the side of the case in numbers the style. ie: 741, 742. and 489. I'm a 489 guy myself.
Small Block
 
Yep, get as much as you can or as complete as you can, drum to drum. Like "small block" said if you get one with BBP, someone will trade you for SBP axles, so no worries there. Good luck! I was going to say wear coveralls.....but I see you are in SD!! Lucky SOB LOL
 
i am interested in this also what cars should we look for to get these 8 3/4 that will swap right in along with disc brakes for the front.
 
'66-72 A-body for 8 3/4 rears and Kelsey Hayes discs if you want to keep the 4" bolt pattern and no modifications. You'll need to get the driveshaft too if it's the same make or shorten your old one.
 
I would think that your odds of finding an A-body 8 3/4 in the wrecking yard are pretty slim.

Early (65-70) B body rears will also work if you're planning on running rims that you can get with more backspacing, the rear ends are a little wider, but most modern rims have more backspacing anyway so it works out.

More than likely, all you're going to find is truck 8 3/4's. They'll work just fine, but you'll have to have them narrowed. Then you'd have to find yourself a set of axles. Depending on the style, the truck ones can be shortened. But, if you're going to do all that work, I'd grab a dana. Believe it or not, there's usually quite a few truck Dana 60's in the yard. They'd need the same things though, narrowed and axles. And truck Dana's don't have pinion snubbers, but that's a minor detail that can be fixed.

I was able to score a complete 8 3/4 out of a '65 Polara a couple months back, but it'd be too wide for an A body at 56 3/4". The yards don't usually have a ton cars that are earlier than the late seventies. You might consider looking for a 9 1/4, they're more common in the model years that are in most yards. Im not sure about the widths though. Early Dakota's might be close for widths.

Also, if you're going to be pulling the rear end out of a car in the yard, bring something to deal with the U-bolts. They'll probably be stuck something fierce, the ones I tried were. Think along the lines of a battery powered impact wrench or sawzall. If you don't have those, get a 1/2"-20 die, so you can clean the threads below the nuts. Even some of the ones that will turn will lock up before they're all the way off. I thought I'd be good with a breaker bar, but I ended up having to cut two of the u bolts to get the 8 3/4 I pulled.
 
get there early, im guessing you arent the only one that will be looking lol (im in co so no worries there). the pull n pays here have 20 intrepids and 50 minivans and nothing older that 85. outside of that ,there are a bunch of old dodge trucks that are 90% 3/4 ton. good luck with the search,and remember the 8 3/4 has no rear cover.
 
Perfect with the info guy's really appreciate the help. Now is there certain car's we can look for that have front disc and power booster thanks again.
 
I haven't measured but I don't think the Dakota rears are any shorter than a full size truck rear. They just put those wheels on them that are almost all the backspace as the width. Plus they put 6 bolt axles in them. A pain in the *** all the way around.
 
And dude, if you find an A body 8 3/4 at your pull-a-part, by a lottery ticket on the way home!!! you never know!!!!!!
 
Guitar Jones said:
I haven't measured but I don't think the Dakota rears are any shorter than a full size truck rear. They just put those wheels on them that are almost all the backspace as the width. Plus they put 6 bolt axles in them. A pain in the *** all the way around.
Click to expand...

I haven't measured one either, they may not be much smaller. The 6 bolt axles are the later models though, early Dakota's (87-91) had a 5 bolt set up. Still, you'd probably be in the same boat of having to narrow it anyway.
 
Thanks for all the help guys! Only ran accross one a body and the rear was gone. Some guy that worked there told me him and a bud took it the day before, uncool.
 
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