dont they use spray glue to adhere them to the backside. Its been a while for mine too. will have to go back and look at my duster's kick panels.

 

Plastic "trees" push in type fasteners, through the insulation and into the firewall.

 

Oh those kickpanels, I thought he was talking about the side kicks {in front of the door}. Yeah the plastic trees have to be destroyed to remove the insulation, hence they must be replaced to replace the insulation. I think yearone has them
or R/T supply. They look like little X-mas trees.

 

The insulaton just rests inside the side panels. Or some spay adhesive.