Doc's 76 Four Door Valiant
Thanks for the comments guys, it's good to have a modern fuel door. Finding a donor car was difficult, all the bone yards want to sell the whole quarter panel that has the fuel door. Finally found one that was off a base model Challenger with a standard flip up fuel door that they didn't care so much about. Under the standard fuel door is the same recessed metal on Hemi cars that you need to do the job. I also got them to throw in the fuel filler neck, you just need the first few inches of the filler neck down to where it tapers off to a much smaller tube. I cut mine off at the small taper and after a bit of clean up it fit perfectly inside the Valiant's original fuel filler tube. You need to do this so that the Challenger gas cap will thread into the fuel filler tube.