CoastalRyan

1970 Olds Cutlass Supreme

12 bolt cover
10 bolt carrier
8.5” gear
No clips on the axle
28 Spline

Stamped CFD8 and 402227 on the outer housing.

Gonna put 3.42 in it.

So to be forthright I’m a novice so most of this is out of my wheelhouse.

Summit says it should be 8.2 not 8.5 and there should be clips... so it must be some kind of an aftermarket non original swap etc

Local place says it should be a 10 bolt cover and they’re not sure either.

I’m pretty sure it’s the original axle but I’m kinda stuck on what posi to buy because no one can put me on the right part.

Maybe someone here can link me up to the right Posi and I can just order it and be done.

Any help is appreciated.

Fun71

You have a 1970 O-Type rearend, which utilizes an 8.5" ring gear that is different than the 8.5" corporate 10 bolt.

The only posi carriers available for the O-Type are original GM or aftermarket Ford 8.8 carriers that are machined for the O-Type ring gear and to fit into the O-Type housing.
There are limited aftermarket gears for the O-Type as well - they ARE NOT the same as the 8.5" 10 bolt gears.

Supercars Unlimited is one source for the modified Ford 8.8 carriers:
https://www.supercarsunlimited.com/1...iers-i275.aspx


Jim at JD Race (goes by monzaz on Classicolds) may be able to help you as well with both gears and carrier:
http://www.jdrace.com/

Richmond Gear web catalog for the O-Type gears:
https://www.richmondgear.com/wp-cont...n1.pdf#page=32

CoastalRyan

Okay thanks. I sent a PM to Jim. Appreciate it.

70W-32

You can also reach out to Brian Trick on face book, he rebuilds all axle types, and can fill you in on the correct parts for your O axle

joe_padavano

Word of advice: The Summit catalog (and Jegs, and Rockauto) is NOT an authority on Oldsmobile cars and parts. Pretty much everything you see there assumes that every GM car on the road is a Chevy. If you search for parts for an Olds 350, you'll get parts for a Chevy 350. If you call their tech line and ask about a Type O axle, you'll get deer in the headlights.

CoastalRyan

Problem solved. Jim squared me away with exactly what I need. Big thanks to everyone for their help and advice.

olds 307 and 403

Best way to go. Summit does carry one, Jim probably is cheaper. I would like to run a 80W140 synthetic, so when I want to do my gear swap, I may see if he can do a Trutrac posi.