70 only had the oddball 10 bolt/12bolt cover rear called the type O
71-72 shared the same axle as the 71-72 buick skylarks/gs which is a 8.5 10 bolt rear, with 3in axle tubes bolt in axles(not c-clip like chevy crap) and most likely 2.56 gears lol(could be wrong on the gear ratio)
