1950 Chevrolet 1/2 ton?

You cannot easily use any part of the torque-tube drive-train with a 1955 or later model rear end.

What are the reasons for the upgrade?
Better cruising RPMs?
What size 16" tires do you now have?

You can use your existing drivetrain with the following "upgrades"/adaptations/changes to obtain lower RPMs at higher speeds.

- change from 4.11 ring&pinion to 3.55 ring and pinion
(16% lower RPMs when cruising)
- change to 16" truck radial tires (31.5" rolling diameter vs your < 28" rolling diameter)
(another 12% lower RPMs at higher speeds)