Are there any? If so what? I got a pretty mint front valance that I believe is off a later 72-74 Challenger, not sure how to tell what year and vs AMD or if it even maters.

The only "possible" difference that I can think of is the mounting points for the anodized trim piece. In 70-71, the trim piece is two pieces. 72-74 it's one piece. The mounting tabs might be in a different place...not sure though.

70-72, the front license plate bracket mounted directly to the valance. In 73-74, the bracket was mounted to the front bumper reinforcement. Are there screw holes in the valance for the license plate bracket?

The 70-71 valance has two bolt holes for the license plate bracket on the inside lip.

The 72+ has 4 bolt holes. The two additional holes are on tabs that on a 70/71 part just has a small ~1/8" screw hole for the splash guard trim.

Cool, it looked pretty similar to my '70 one. This one does not have the 2 licence plate holes my '70 has, which is a bonus in my mind as I don't run a front plate anyway. This one did have a different part number by where the reinforcement bracket meets the valance.

Yes they look the same and 99% of people don't know the difference