I have a 1941 1Ton and I was able to fit 1/2 ton Disk brakes on it without changing the front axel out, I was still able to use my original 6 lug 17" rims. I discovered that the 1941 1 Ton,1/2 Ton and 3/4 Ton used the same front end by comparing all the numbers in a factory parts manual.
As for the rest of the truck I installed a sb350 engine, 700R4 Transmission and a custom rear end with 3.90 gears.
I am puzzled that you have the stock 1 ton fenders with no cut out for the 20" wheels.
What is the allowed load weight stamped on the Vin Plate?
