Jim,
Check my link bellow for pictures and some info on swapping newer disk brake axles in a 1.5 or 2 ton AD truck. Can also fit .75 and 1 ton but the wheels look wrong.

I am a fan of using the old frame, they are plenty strong. I think it makes a cleaner, more profesional job to swap better running gear to the old frame than to swap the cab to a new frame. I also think it is less work to just swap axles.

Grigg

PS, I also like diesels, Detroit Diesels more than any, and am swapping a 4-53T in my 48 2 ton.

•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-