rear differential

I just bought the truck ant haven't brought it home yet. I'm just wondering what the rear end was and if I could put an electric locker in it? It is a 4 speed in the floor. I am going to put disk brakes all around.

from A,B or F/M/J body. Don't care about gear ratio or carrier. Needs to be in working condition Bill in Winston Salem NC [email protected]

My daily driver is a 1957 dodge d200 5.1L v8 ....So my rear end started making whining noises only in 4th gear when accelerating....i know its hard to say what it is without hearing it . Any suggestions to what would be causing that? Since im already going to be working on the rear end is...