Interesting as I had a 70 Challenger V5X car and the side moldings are so different just a year earlier.

The 70 used a stud on the body line to hold a plastic clip. On the ends of door pieces there are holes where the molding uses a clip and nut combo. On top of that. the molding are bent to match the application.

I recall mine where shot so I went out and purchased the rubber style. I had to grind down the original studs but once that was set they installed in no time.