Unless there is one out there that was garage kept its entire life, I doubt that there would be much original primer left under the cab.
I do know where there is a 52 firetruck which has spent most of its life inside. I'll need to do a road trip and crawl under it.

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