@robert ruggles,
When I removed mine when I was rebuilding my truck, I remember there were these nail head looking things that the back of the molding was attached to. They weren't screws I don't believe, they looked like the head of a small nail sticking out from the skin. I wonder what those were? We just ground them down flush with the skin. Now, my truck is a '74 Custom Deluxe Ten. It had all the trim, back of the cab, all the wheel well openings, trim down the middle of the whole truck from back to front. In order that we wanted to make the body smooth we removed all of it. All of it was screwed on except that is the back of the cab. None of it was screwed on. It was attached by those pins. I don't remember about the side pieces of the cab. There may have been a screw or two somehow.