Joe, I have a 69 Cutlass conv. Wanting to beef up diff. It has a 12 bolt cover and a 12 bolt ring gear. The axles are 28 spline. No positract. Is this possible or should I be looking for a different housing? Sorry. 10 bolt ring gear

 

I gave you your own thread because this is unrelated to the thread you hijacked. You have a Type O axle. Parts are not easy to come by. Your call on whether or not you want to build this axle or start with something easier to get parts for. How "beefed up" do you plan to get? What will you be using it for, street or track? With slicks or not?

 

Are you sure it's a Type O? The ring gear having 12 bolts would suggest it may be a Chevy rear.

EDIT: Whoops, never mind -- just saw your edit.

 

There are aftermarket limited slip differentials available for the O-Type rear. These are Ford 8.8 carriers that are re-machined for the O-Type ring gear bolt pattern. I think they are compatible with the 3.08-3.23 series gear sets, but I am not 100% on that.

 

I'm so embarassed about this thread. I hijacked a thread and then gave false information. And now I'm changing information again. It does have a 12 bott ring gear, tapered axle housing at drum backing plate. It also has 28 spline axles. The small axles are my question. I want to add a positraction, and 4.11 gears. Seems that most posi units are for 30 spline axles. It's going to be mostly a street machine but I'm also adding nitrous. I'll also have a pair of slicks or at least drag radials. Thanks for your replies and patience.

 

How about you post a photo of the cover on that axle, so we can stop guessing which axle you have.

 

 

Chatt, this is the 12-bolt Chevrolet type rear axle that uses the 'C'-clips. There is a pretty decent aftermarket support for finding parts for these. Monaz in this group would be able to help quite a bit in getting what you need.

 

So you are saying your axles are 28 spline?
I would recount and be sure.
IF they are 28 spline someone has modified the posi unit which is REALLY weird...as all 12 bolt c-clip chevy rears were 30 spline. Period.
Please recount and make every spline and try again. Jim

JD Race
we have all parts to rebuild posi it up and gear swap that rear.

 

30 splines. All a 'go' for upgrading. Thanks for all the help!

 

LOL.... Yah it is ok...We all are covid screwed these days...LOL.