I have a 57' Chevy sedan with an Olds rear end that has a bearing going out. I am hoping to get some info on how I can find out what this rear end is out of (model,year).
Thanks in advance for any info.

 

The cover tells me that it could be a mid 60s ten bolt 8.2" ring gear Buick or Pontiac diff. The Buick had one horizontal stiffening rib going to the pinion nose on the driver's side and the Pontiac had two which converged at the pinion flange for the driveshaft. It could also be an 8.5" ring gear diff from 1971 up. Hopefuly someone recognizes the casting numbers.

 

That is a full size pontiac 10 bolt cover rear with 12 bolt guts 8 7/8 ring gear. Does it have bolt in axles or c-clip axles. If you get me a shot of the backing plates from under the car I can tell you.

It looks to be posi as the tag is there. Best ratios for this rear I think was 3.42 if it is a c-clip type and the bolt in axletype from the late 60's the best ratio that you could get was 3.73 ...

The pictures show the 1971 -1977 12 bolt with 10 bolt cover posi units. The older late 60's units will look about the same except they only have 2 preload springs.


NO AFTERMARKET SUPPORT FOR THESE REARS AT ALL... No posi unit No gears. what is out there is what you rget. Jim

 

Thanks Jim. That's alot of valuable info. I know it is a bolt up,not c-clip.
I will be taking it to a shop to diagnose a "rolling-groaning" type noise that may be a bearing. I am worried that there may be a ploblem finding parts, as you said. It is a limited-slip rear end. Thanks for your info,and I may be asking advice on locating parts very soon!--Bill

 

I am here I think I actual have one posi on the shelf for that rear. It has a 3.23 gear on it BUT when it was shipped to me the pinion was LOST! Not good as those 3 series ratios are hard to come by. Jim