G body vs A Body Rearends

08-06-2004, 12:57 PM

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?

GoldOlds · 05-21-2007, 08:28 PM

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.

joe_padavano · 05-22-2007, 09:45 AM

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.

GoldOlds · 05-22-2007, 11:16 AM

Quote:

Originally Posted by joe_padavano

the 7.5 inch axle that was originally born under the Vega.

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

monzaz · 09-13-2007, 09:06 PM

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

05-22-2007, 09:45 AM	#3 (permalink)
joe_padavano Moderator Join Date: Mar 2007 Location: Northern VA Posts: 1,162	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. __________________ Joe Padavano 64 Jetstar 88 Conv 66 442 L-69 Conv 68 W-30 69 H/O 69 442 70 W-30 72 442 86 Caprice wagon (w/307 Olds)

09-13-2007, 09:06 PM	#5 (permalink)
monzaz Senior Member Join Date: Jul 2006 Location: Richfield, Oh Posts: 85	8.5 rear 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

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
1962 Conversion to front power discs	Sixoh	Brakes/Hydraulic Systems	19	03-30-2008 10:24 AM
performance upgrade	sean000	Cutlass	9	12-22-2006 06:41 PM
69 air conditioner compessor	mjscutlass	Parts For Sale	0	12-07-2006 01:12 PM
98 Bravada auto climate control	cliffg8	Bravada	4	10-21-2006 08:42 AM
Electrical	olds75cutlass	Electrical	4	09-22-2006 03:14 AM

08-06-2004, 12:57 PM	#1 (permalink)
<72S> Posts: n/a	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?

05-21-2007, 08:28 PM	#2 (permalink)
GoldOlds Senior Member Join Date: May 2007 Location: Chatham-Kent, Ontario Posts: 116	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.