I bought this rear a bunch of years ago. I was told it came out of as 71 vista cruiser. Both axles spin in the same direction when turned so I will say it is a posi unit? That is the only test I know to determine if it is a posi or not? maybe someone can educate me? Anyways, I sandblasted it and painted it because it was pretty rusty with some heavy pitting. I can't see any codes on the axle tubes because of the pitting and the only casting numbers are the ones in the pix. The break shoes are about 2-1/2 " wide also. When I turn the axle one complete revolution, the yoke turn a little more than 2 1/2 time. Would this be a 2.56 or 2.73 ratio?
I get really confused when looking at the diff. covers on some of these rears so I was hoping someone like Monzaz or anybody could chime in and give me some info. Thanks in advance.

 

I have a clean 10-bolt rear that I would like to transfer everything to if possible?

 

That is a 10 bolt 8.5 rear and should be very strong and great for any type of build up. the guts will interchange with any 10 bolt 8.5 rear from 1971 -1972 Buick or olds A-body and or you can use any 8.5 Chevy posi and or gears in this rear too.

IF you do have 2.56 gears then you will need a spacer and bolt kit to use 2.73 -5.57 ratios. Let me know if you need anything more. Jim