Nick I checked the GM Heritage Center website for the technical specifications of the 1939 and 1940 production years.
The drawing for the ‘39 half ton truck body shows the inside bed measurements the same as posted above for ‘37 and ‘38. See the attached drawing.
Unfortunately, the 1940 truck information given on GM website appears to be missing the drawings that would show the measurements needed. In checking the website for the Old Car Manual Project those same drawings; and others, are missing as well.
I wonder if the AACA club library has the complete information? The Vintage Chevrolet Club partnered with them some years ago to store their collection.
