Can someone tell me what this posi carrier is for. I am being told OLDS 12 bolt. I am trying to figure out what size olds 12 bolt posi.jpeggears would work on it.

 

Look for a large 3-digit number around the ribs that go to the ring gear bolts. 673, etc.

 

Does it have 10 or 12 holes in the ring gear flange? Olds 12 bolt only has 10 bolt ring gear.

 

Without seeing anymore but if is a a large 12 bolt pattern it could be a 57-64 Pont/Olds 9.3" unit (57-58 is 29 spline and 59-64 is 31 spline axle.

 

Ok well the casting is not listed in my book...? Weird...

But check and see if the spline is 31 or 28
It is mostlikely a Ponitac Full size posi if it is 31 spline

COULD be a 8.75 Full size posi if it has 28 spline and c-clip side gears from the 78-85 era.

IT is a eaton posi
IT IS NOT a OLD 12 bolt posi full size or A-body - THAT IS A FACT for certain.

Cover of the rear will look like this that the unit fits...

Not the greatest of pictures i will see if i can do better. Hang on...