By the way, I forgot to mention to unscrew the rear retainer off of the ball collar before trying to slide it back.Try a hacksaw blade laid flat and slice off the grime or an old wood chisel and patience on the caked up grease and grime.
I think your 4 speed will be the open drive type, with u-joints exposed. That will not work with your torque tube. If you can get the rearend and driveshaft that was with the 4 speed trans and that should work, but then you get into what kind of shocks are on the donor rearend. If they are both knee action type it could work.
Let me vision this, engine is out, trans and torque are still in. If the trans is bolted to the frame cross support, it should work like we suggested. After you get the rear of the ball collar unscrewed just work it/slide it back. Unbolt everything as above and the trans should be free.
