ziff396

What are the pro's and cons of each? I have a 72 corporate open with 2.73's and also a O rear with 2.56 gears out of a 70. Both are out of Cutlass's.
Which would be the best choice to rebuild and convert to posi units with 3.42 gears? I'll be running a strong street 455 with a turbo 400 trans.
Thanks for any help!
Kevin

72 Cutlass in progress.

BILL DEMMER

from what i've always heard, the availability of parts for the O are poor.
i know the guy that did mine thought more highly of the corporate r.e. and had some difficulty locating the parts for my O r.e. but, he got it done on time and under budget.


bill

joe_padavano

Strenght-wise they are pretty much equivalent. Both use an 8.5" ring gear with ten bolts. The parts availability pushes the corporate axle to the top.

BILL DEMMER

joe,
i thought the type-o was 8.2" and only used 10 bolts on the ring gear to carrier vs. the corporate 12 bolt with an 8.5" and 12 bolts for the ring gear to carrier.


bill

Run to Rund

Thre were type B and P 8.2s used in 64-7. Type O was 8.5, ten 7/16 left hand threads (iirc) on the ring, 12 bolt cover, from May 66-70; thru 68 with 31 spline, 69-70 with 28 spline axles. Corp 8.5 was mostly 71-2 in terms of mounts for 64-72 A bodies, with 10 cover and ring gear bolts.

For best strength, the corp 8.5 has the most stuff available, as noted above. Many weld the tubes to the center section with nickel rod, but it should be done by someone good and carefully to avoid drawing the tubes out of alignment.

I did a cost comparison a couple years ago with the 8.5, 12 bolt Type C, and Type F ten bolt (9" Ford). Mild builds--you can save if you already have something to start with. Full builds, pretty much the same cost for all of them.

joe_padavano

Bill,

The 8.2 is the earlier axle. The 67-70 Type O is 8.5", 10 bolt ring gear. The Corporate 8.5 is also ten bolts on the ring gear. The Chevy 12 bolt is an 8.875" ring gear with 12 bolts.