1973-1976 A-Body door parts needed

Uhhh.....

Swinger is longer than the duster and dart sport.

If you're referring to these:

1712685509279.jpeg

...You are confused.
ALL 1973-76 Dart, Valiant Scamp, Duster and Dart Sport models use the same upper door pads. All of them. The doors all interchange but the windows are different. The Duster and Dart Sport have curved glass, the Dart and Valiant Scamp are more straight.