I take it you don't have the original kick panels. There were two different kinds, carpet with bound edges and plastic panels. They were different depending on if you had factory air or not. I'm sorry, but I don't remember how they were attached.

 

Plastic Kicks

I take it you don't have the original kick panels. There were two different kinds, carpet with bound edges and plastic panels. They were different depending on if you had factory air or not. I'm sorry, but I don't remember how they were attached.

You are correct, I don't have the originals, which were all plastic!
I have reproductions, also all plastic with no holes for mounting!

 

O.K. If you have reproduction panels then there are holes to attach them in your car. In other words, if they were attached with screws, there would be evidence of that, and if they were attached some other way there should be evidence of that too.

Are there 1/4" or slightly larger round holes next to the door opening? If there are, then the kick panel was attached with panel fasteners. If not, there should be smaller holes if they were attached with screws. If there are no holes, the panel probably fit under a retainer strip, but even that would have holes that held the retainer in place.