66 and older a-body cars had a different sill plate. One goes on the metal door jam itself. The one the OP is asking about is called a "carpet hold down" and goes on the inside where the carper meets the inside jam/windlace seal.
I believe Laysons makes them both, I would contact/PM FABO member Rick@Laysons, he is a great guy to deal with and the only guy to deal with when it comes to Laysons, tell Rick "Keith" sent ya!! :glasses7:
