My friend who bought the 1973 Charger SE that I've mentioned on a previous thread wants to find an 8.75 rear differential for this car and is having a difficult time finding one from a 1971-1974 B-Body car, but has been able to locate a couple of 1969 8.75 assemblies for very good prices.

The 71-74 B-Body cars use an 8.75 with a 489 case that measures 63 inches from brake drum to brake drum and so do many of the 70 and 71 C-Body cars, so here's my question. If we end up not being able to find a 71-74 B-Body, or 70-71 C-Body assembly at a good price, would it be possible to use a complete assembly from a 1969 Plymouth GTX that he's found with a differential that measures 60 1/8 inches from brake drum to brake drum with a 742 case in his Charger with that much of a width difference? Could we handle that difference by using aftermarket wheels with back spacing to offset the width difference?

We do understand that the leaf spring to differential mounting seats will have to be moved and that the 69 and 73 differentials have a slightly different mounting procedure that will need to be addressed, but would there be any other issues with this swap?

Thanks for your quick help in advance!