How are the rocker molding clips ( Clip - Moulding / Trim - Rocker Panel - PLASTIC - EACH - NOS ~ 1969 - 1970 Mercury Cougar ( 1969 Mercury Cougar, 1970 Mercury Cougar ) at West Coast Classic Cougar :: The Definitive 1967 - 1973 Mercury Cougar Parts Source being attached? Screws, rivets or maybe this: Ford Body Glass Vinyl Top Trim Molding Spot Weld Stud Rivet In Studs 10pcs LO | eBay
I used stainless rivets.
I had to drill mine out, so I know they were pop rivets ( San Jose Assembly - so they were used from the factory ). I too replaced with stainless steel pop rivets, as some of the originals were a bit corroded ( but they weren’t that bad, even on the passenger side ! ) Good luck with the job.