Rear end swap flop

[CaliCuttie]

Hey guys, just had a rather frustrating weekend trying to get what I was led to believe was a 3.73 8.5" 10-bolt posi rear end from a Grand National into my 86 Cutlass. Turns out the rear end was not a direct swap, upper control mounts on the rear end are too wide for my control arms, and the shock absorbers mount to the front instead of the back of the rear end. Needless to say I'm back to my old stock rinky dink 2.14 one-legger, and I'm sure this will keep my dad from helping me do a rear end swap ever again 😳
So aside from obviously selling it what other options do I have? Can I work with my current rear axle and theoretically get a 3.73 posi unit in there? I'm not sure how the actual gears work, just how everything bolts up on the outside thanks to this past weekend. Any tips, pointers, etc would be nice. Thanks!

 

[Bonnewagon]

You can get a shop to install 3:73's but it will cost around $500 for the gears and labor, maybe more. Much easier and cheaper to find a rear from an A/G body. Doing it yourself is not a good idea if you don't have the special tools,a factory manual, and a good working knowledge of ring and pinions . Any idea what rear you were sold?

 

[RITTER]

Post a pic and a number off the axle tube from the rear-end you were sold

Sorry about your misfortune here

 

[art]

Well I guess your options depend on what you have. If it is indeed an 8-1/2, you may be able to still use it provided the housing is the correct size. You will need some "custom" upper control arms most likely. Just as a hint for next time, I have never seen an 8-1/2 gbody rear with anything other than metric studs. (12 x 1.5) You now know to look where the shocks mount. The specific dimensions escape me at the moment, but I think it is 52-1/2 inches from flange to flange across the housing. Hope it works out for you.

 

[stomis]

Well I'm curious as to what the hell the mystery rear is out of after reading this...

Post some pics. Also if the rear fits under the car putting new brackets and shock mounts on it is not a big deal to anyone with some fabrication skills. Dont go ditching this rear yet, and also if you are gonna keep a 7.5 then just find a Posi SS rear. 3.73s and posi for like $200 typically on CL.

 

[Oldsmoletick]

Sounds like a B-Body rear, I made that mistake too :lol: .

 

[84cutlass383]

x2 on the b body rear. i found one in a olds custom crusier and i also found out the wrong way

 

[tdvick]

I have a feeling this is a thread dad started on a different website about the same issue. There's some pictures in this one.

http://forums.performanceyears.com/foru ... p?t=644082

 

[84cutlass383]

yep thats a b body rear

 

[CaliCuttie]

I have a feeling this is a thread dad started on a different website about the same issue. There's some pictures in this one.

http://forums.performanceyears.com/foru ... p?t=644082

That is my dad! Sorry I've been so slow to the punch. Well, since I apparently have a B-Body rear end, is there anything I can do with it??