There are always some places where the color will still be lurking. Check to see what original colors were available, then try and find a hidden spot that matches. Look for places hard to sandblast, in the door hinge area, or anywhere two pieces of metal overlap. Some areas that get little wear may have just a single coat of paint over the original color, like the door frame, or in the engine compartment. I think GMC was still matching wheel color to body color in 1950. On my '48 under about three or four layers of other paint, the original color was still there. I realize that wheels have often been changed but if all yours are the same color I'll wager they're the original ones.
