Differential Question

Il Duster,

As far as I know, (which isn't much sometimes), you can't do what you are trying. All of the parts from the center section have to be the same. ie: case, gears, bearings and carrier.
Any case and guts will fit any axel though, except for the very early stuff, pre 62 I think.
dusterdon has the right plan. Pick up a center section out of any 8 3/4 and swap it out when you want. If your just going to use it for highway cruise's, then a one legger will do fine and you should be able to get one for $50 to $100.

Jack