Are you sure it's the original color? If you're not sure you should clean off a spot on the firewall, it's the least likely place to be repainted.
The colors for cars and trucks are not the same and truck colors are pretty distinct. Look
HERE and you'll probably find your color match.
I do think it is an original color as I found a replacement grille at a swap meet that was an exact match.
I have checked out the Aoto Color Library and there doesn't seem to be a match. It is difficult to judge because of the computer but none of the colors seem to be close. I have found some '48 automobile colors that are close or maybe a match but no truck colors.
Again it looks like a sea foam green.
