Well....turns out they had this chrome cover on the top of the panel. And this was covering up chrome sheet metal screws on one side, and regular screws on the other. There was this icky red quilted fabric cover applied to original door covers, but I don't think they came from this truck. The covers are blue and my truck is that funky green.

I kept prying on them until I saw the threads of one screw and thought 'what the he...?' Then lifted the cover and there they were.

I have the interior emptied out enough that I can now paint it white and scrambootch the green. :p