Challenger pan was my first thought, too. But then I started looking at pictures and the fuel filler hole is more in the center (like your picture, HemiOrange70). The hole I'm talking about is just aft the wheel well. I'm sure it's for that tube that runs along the wheel well, but I don't know what it's for or how important it is. The hole that goes into the cabin (second picture) is only a guess that it's related. I just assumed that's where the tube coems from or leads to. Thanks for all the input too, by the way.