Would an 8.5 10 Bolt from a G-Body (1984) work in a 1972 Cutlass A-Body? I understand that the '72 has a 10 Bolt (8.5?), but it's a 3:08 open diff. The 8.5 is a 3.73 Posi. Could I swap the G-body rear into the A-body?

 

I could be wrong here, but I think most G-body ('78 to '88 Cutlass, Monte, Grand Prix, Regal, Malibu, etc.) rears have 7.5" rear ends, not 8.5". The 7.5" is the weakest rear end GM ever made. The only G bodies that had the 8.5" rear were the 442s and Grand Nationals/Turbo Regals.

 

While there are a few 8.5 inch axles under G-body 442s and Turbo Buicks, almost all came with the 7.5 inch axle that was originally born under the Vega. More importantly, the G-body axle is about 3 inches narrower than an A-body axle AND the control arms are at a different angle. You can physically force them into place but the suspension will bind up if you try to drive it.

 

That's exactly where those P.O.S. rears belong! Too bad the G-bodies didn't ALL come with the 8.5" rear - otherwise, they're great cars.

- GoldOlds

 

What I could never figure is how camaro and trans ams got totally left out of the 8.5 loop??? That was weird. JUST a thought. Jim

 

Someone was making control arms for the 12-bolt into a G body - don't know if it'll work the opposite way, though!
If that's watcha got to play with - make it work!!