I've got a 71 in the garage that I'm fighting with now.

FWIW my car came with a filler that mounts to the outside of the quarter panel. It went right in with the tank strapped in, but the gas cap stuck out off the side of the car. I believe those are for later model Dusters or something but they won't work with the 70-71 quarters at least The gas caps are different too.

I bought the right filler and cap for my car, but can't get the tube to go into the tank. The FSM is no help with installing it either. The only specific instruction is to rotate it 180 once you get it in the tank (or before you pull it out). No wonder they redesigned it, because it sure seems impossible to get the filler in the tank to me. If anybody knows the secret, I'm all ears.

I've tried loosening the tank a little to try to change the angle the tube meets the tank but had no joy. I guess my only option is to drop the tank and try to get it in. I'm not even sure the thing will reach all the way through the trunk grommet down to the tank, if the tank is on the garage floor, but here I go to find out.