I don't have a 1/2 ton, and don't plan to..
But I would swap the whole rear for a more modern one, for several reasons.
Better brakes, with easier and cheaper to get parts.
Loose the torque tube.
Cheap and readily available gears in many different ratios.

There are a number of rear axles that will work, and a search of this site will reveal them. The biggest thing to look for is one that is narrow enough, as most will be to wide. Will also want to consider bolt pattern and the wheels you want to use.

Just my thoughts, with no experience behind them....

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-