It's possible yes,

Some will be simpler and some better than others, what engine do you have in mind?
Also depends on what you want to do with the truck.

In general a 1/2 ton is on the small side for most 6 cylinder diesels you'll readily find. lots more suitable 4 cylinders though. Or step up to a larger truck and stick with your 6 cylinder ideas.

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-