Hello all,
Will a 10 bolt posi unit from a 81 Chevy El Camino fit my 72 Cutlass supreme. It also is a 10 bolt.

 

I'm no expert on this, but I can tell you that the '81 should still be an 8.5 ring gear. GM went to a 7.5 gear in '82.

I also have an '82 El Camino in addition to my '71 Cutlass SX.

 

Sorry, that is not correct. ALL 1978-88 A/G body cars used the weak-kneed 7.5" axle (originally born under the Vega) except the 1984 H/O and the 1985-87 442 and GN. Aside from the fact that this swap is a downgrade, the later axles are about 4" narrower and the ears for mounting the upper control arms are at a different angle than on the 64-72 cars. Don't waste your time or money.

 

That would be 3 strikes and your out.
your 7172 cutlass is 8.5 and the 81 el is 7.5

Totally different 10 bolts.

there are SOOOO many 10 bolt rears just in Gm it does get confusing.

10 bolt 8.2 Buick
10 bolt 8.2 chevy
10 bolt 8.2 pontiac
12 bolt cover with 10 bolt ring gear (which is 10 bolt rear) AKA 12 bolt 'O'
10 bolt 7.5 car and light truck and H-body
10 bolt 7.625 car and light truck
10 bolt 8.5 Early, Late car and full size truck
10 bolt 8.625

All the 7.5 7.6 etc are ring gear diameter measurement to id the rears and give them some kind of reference.

Hope we all have helped you.

You need to look in 1970 -1981 camaro firebirds
73-77 a-body GM
1971-1987 full size cars with the 10 bolt 8.5 rear under it. wagons buick olds pontiac chevy impala etc.
Watch out for truck locker units they will fit but are really not for spirited driving and burn outs. They are more for pulling snow mud ice etc.

Good luck in the hunt.

If you get tired I have them on the shelf. It is best if you just buy anew unit if your keeping the car as they are WAY stronger than any stock GM unit.

Jim
J D

 

Thank you guys for all of the help. I think I may just go ahead and go with you Jim. LOL!!!!
What are the prices looking like?

 

Sorry for the wrong differential info there, I stand corrected. (now I'm trying to remember where I heard that in the first place)