Vinyl top trim fasteners - looking for source

The car is a 1970 Dodge Dart. This is NOT about the readily available trim clips that bolt on at the bottom of the back window!!! On my C pillar the trim is secured by odd screws that the trim clips directly over the head.

Below are some pics of the old rusted screws that came out. Again, there is no molding clip attached to these screws, the vinyl top trim just clips right over the head of the screw. Anybody who knows where to find/look for these, I would appreciate you responding on the thread. I've been looking for months! If anybody even knew what the name for a screw head like this would be, that would help. The head is exactly 5/16 of an inch wide at the widest part.

Thanks for any help!!!!

dsc00951-jpg.jpg dsc00953-jpg.jpg dsc00954-jpg.jpg