gt-6 diff in a 75 spitfire?

["rstieg" <rstieg@ci.bartlett.tn.us>]

Since I have a half-inch "play"in the diffy on the car, I looked in the
attic and what did see, but a gt-6 diff and several bits of
drivetrain. (friend moved and I agreed to 'store' the stuff)  He said the
spider gears were welded and the thing was under a spit
x-crosser.  questions:
        1. does it "bolt" right up-is the splines on the driveshaft the same?
        2. what about a 'solid' rear end with no posi-track for the street?
thanks in advance.
rick stieg '75 spit