Check out this thread again,
This is what I know about swapping disc brakes on an AD 2 ton truck front axle.

I haven't looked at the rears because I think swapping to a whole newer rear with more gear options is a better plan.

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-