URGENT! Gas cap for 71 Duster

I just stumbled across this thread. I have an early 71 Demon SPD 925 but from your reference pictures I have the 72 and up cap with a filler tube that screws in from the back and my cap sits perfectly.
My filler tube has 3 screws and a vent line that is just sitting open under the trunk floor.
Oh and before we start a stripe thread I realize the cap should be painted including the handle and the stripe moved up accordingly.
Any thoughts?
Thanks
Ron:burnout: