Originally Posted by Hermes1
The problem with plastic linings is twofold, they do not seal out moisture so moisture gets trapped between the liner and the bed. Secondly, they tend to shift and move around which scratches the paint, typically to bare metal. Compound the trapped moisture and bare metal and rust usually follows. I had one on my first truck back in the 80's and I had to remove the liner for another reason and was appalled at what the liner did to the bed.
Ditto on my '90 Dakota. There were rust "pin holes" straight through the bed when I removed mine.