7 1/4 to 8 3/4

As long as it's an A body 8 3/4, you will have no trouble with the swap..Some things to think about tho..I dont think the brakes(backing plates) will interchange, but any other rear w/10" drums will. Also, the shock plates are diffferent, because the axle tubes are 3" on the 8 3/4, and I think 2" on the 7 1/4. you will also need new U bolts, and if the 8 3/4 was from a racing car, the yoke may be larger(the u joint).