It's been a while since I've had a Duster apart, but this is what I come up with for a '72 fill tube:
View attachment 1716452100
Pardon Our Interruption...
Doesn't look like yours.
And yours isn't installed correctly- it gets installed from inside the quarter panel with the foam seal sandwiched between the quarter panel and the filler flange. That should take care of the height issue.