Search this site for diesel conversions, there are plenty of threads already covering this.
I am putting a Detroit Diesel 4-53T in my 48 2 ton. check out the pictures in the link below.
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-