Scamp License Plate Light

Restoring my 1972 Plymouth Scamp and having a problem finding the correct license plate light and mounting bracket. The mounting tabs appear to be under the rear bumper and the holes are 3 3/8" center on center, there does not appear to be any additional holes on the valance that would allow for mounting a bracket/light. The valance has the square holes for the license plate push in mounts. Any help would be appreciated.
The bumper and tail lights were like the 70 Swingers.

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