I know cars are different from plant to plant, however if they used 2 completely different methods of attaching these moldings than there would have to be 2 different type clips to install the moldings. The stud type way would need a larger hole next to a smaller hole so the clip can slid into position. The rivet type would only need one hole for the clip. Anyone else want to weigh in on this one?
As far as rust prevention, that would be a toss up, you weld a stud in and there is really no way to treat the backside of the rocker and if you drill a hole and the paint chips when the rivet expands it can cause corrosion. I myself would prefer the rivet type, however I don't think either one would be a problem.