I carefully measured my 51 GMC 1 ton and I think all AD trucks would be very close if not the exact same.
If the rear part of the frame were level, the part under cab and bed, (not the front frame beside engine which slopes down.)
The engine is tiled back 3.5*

•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-