It works on the ‘Cuda’s and Chargers because the plate is in the tail panel, above the tank.
On a Duster the plate being on the bumper means it’s also below the top of the gas tank. Not gonna work.
You’d have to put the filler in the tail panel to get it high enough, so, you’d have to rework the tail panel to put the plate there and then rework the bumper to remove the plate mount. Or do some kind of gas filler door in the tail panel.
I gave it some thought because my ‘71 Satellite has the filler behind the plate. On a Duster it would mean a bunch of bodywork to the tail panel at the minimum.