Scamp bumper?

Duster & Dart front bumpers are not the same. Dart Sport has a bigger point or beak. They just both gained the extra license plate carriage bolt locations when they went to the "shock absorber brackets".

Dodge Dart Sport can also interchange with Dodge Swinger, Custom, Special & SE as long as the mounting configuration is the same.

The rear bumpers went through the same transition on Dart Sports & Dusters (Scamp, Swinger, etc. are totally different.) Normally, '73 & older use standard brackets. The '74+ I've seen have the shock absorbers but late '73 models may have started to change. Just check the brackets.

Just to clarify, in this case, Dart Sport and Duster only rear bumpers will interchange as long as they have the same mounting configuration.