Got a question about the finish on the underside of a Sept 22, 1964 fastback. I was under it last night scraping old undercoating off of it and it looks like the bottom of the tunnel was painted with some sort of paint that is kind of similar to the exterior color. The car is color code 5 (Twilight Turquoise). There is signs of the original turquoise on the rear frame rails to. The car was built on Sept 22, 1964 in Dearborn.
What color should the underside be? I can't find any sign of the typical Red Oxide that most people seem to do the underside in when they don't undercoat them.