Im taking the type o diff out of my 69 and replacing it with a posi 8.5 out of another a body. i have looked at a bunch of forum answers and cant seem to find a strait answer, will the u joints be the same? Will driveshaft need to be lengthened? should i just find a driveshaft off a 70+ cutlass and swap it.

 

The driveshaft will need to be shortened.everything else is the same.Just make sure you are getting an 8.5" and not an 8.2".the 71-72 Cutlass/442 and 71-72 Skylark/GS were the only ones that came with them originally.Pontiac kept the 8.2".Chevy supposedly started using the 8.5",but I have looked under plenty of 72 Chevelle's,and they all had 8.2's,plus they are a c-clip rear.

 

If I read you correctly, you are taking the type O rear end out and replacing it with the corporate 8.5 rear end from another A body that became available in 1971. If that is your plan, it should work out fine. I did the same thing with my 70 Cutlass wagon. The bearings went out and I swapped in a 8.5 rear end from a 71 Cutlass four door. You must use the driveshaft from the 71, as the rear end housings have different dimensions. The yokes are not an issue as they both mate up to the Turbo 350 tranny. That was my experience. Hope that helps.