A '47 cab has a more substantial center brace at the rear of the cab preventing a later model gas tank from fitting behind the seat. This extra bracing supports the center rear cab mount below it. (Models from '49 forward, had two rear cab mounts of the shackle style.)
'47 will also lack a hole in the cab for in-cab gas tank filler neck.
A '47 3/4 ton chassis would have come with a 125 1/4" wheelbase, 8 lug split rims, and lever action shocks.
1 tons had a 137" wheelbase.
Carl
