Chit if I know. The A body used the 8 3/4 with the small bolt pattern only until 1972. In 1973 they dropped the 8 3/4 for the A body and went with the 8 1/4. How certain are you that what you have is an A body 8 3/4?
Who cares what year the axle came from. Early cars had 8 3/4 with SBP. If that is the pattern on the car, that is what he needs.
If you order axles from any of the manufacturers you spec what you need. If you have C clip axle retention and intend to race, many sanctioning bodies require the big Torino ends and pressed on outer bearings and retainer. They make the axle to fit the bearing for any housing and width. Splines are speced also.
