Check out my pictures on the link below.
I have installed disc brakes on my 2 ton.
It can be done, it is not simple, but well worth the effort.

Basically it involves finding a newer front axle like from a step van with the same bolt pattern, 5 lug front and 10 lug rear is my guess as to what you have, then narrow the axle to make the tires fit in the fenders.

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-