My vote would be an 8.8. They are plentiful and cheap at salvage yards and already come with disc brakes! You could probably buy 3 of them for the cost of A body 8-3/4 set up with a locker and discs!
While any Mopar I do personally must be Chrysler powered, the 8.8 is the way to go.
An 8.75 rear for an A body is stupid expensive and you are stuck with small bolt pattern axles.
Pricing everything out, an 8.75 spec'd like I want it would be at least $1500. The 8.8 would set me back maybe $600. It is also crazy stout power wise. Gear sets are low cost as well.
At the end of the day, it's a rear end and all it has to do is work.
