A body rear
I talked to Dr.Diff about this at the MATS show a few weeks ago. He said the housing ends are the same but the studs are shorter and need to be replaced to use the non tapered aftermarket axles. He has the studs. Don't know what brakes you plan using but the 63 backing plates are different. If reusing the 10x2 1/2 shoes/drum use the 65 up backing plates.
The chart I have shows 62-70 8 3/4 B body flange to flange is 55.000 compared to the A body 8 3/4 at 51.400.
I have seen these specs to be + or - do to manufacturing tolarences.
This chart was printed in Mopar Muscle Mag years ago,,, Values ?