It is for a J-hook for the under-bed spare tire carrier. It wasn't used for the '51 and later trucks, as the design for the carrier was changed. They did not change the dies for this piece of sheet metal, so the hole remained. Well that's my best guess anyway.
Carl


1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission