Some interesting info starting
here. Appears to be scans of pages of a 1954
GMC produced parts book with identification of models by serial numbers. Scroll to the bottom for the original sources.
This page shows that in 51-54 they
did make long bed 1/2 tons, did
not make short bed 3/4 tons, and long and super long bed 1 tons. Interestingly enough, it also shows that they made swb (116") 1 tons in 47-50, and starting again in '54. However, it's possible that those were only sold as cab-n-chassis, say for a tow truck setup or similar.
I do realize the OP was asking about Chevy, but GMC was brought up so I thought I'd throw this out there.
