70-76 Duster Valiant fenders are different. 73+ have a different mounting setup in the headlight bucket area, IIRC. Additionally, marker lights differ on the 70-71 and 72+
I was thinking about this. Some of the cars that will have the same basic fenders as a 73 Duster:
72-76 Duster/Valiant
72-76 Scamp
Different markers:
69-71 Duster/Valiant
71 Scamp
Any hood from a 69-72 Duster/Valiant or a 71-72 Scamp would work