All, I am planning to put some plastic bed rail caps on a truck I am buying to cover up some scratches. I am also planning to put an RKI low profile toolbox on it. Can a toolbox be installed over the plastic bed rails caps or will it deform them? I guess if the answer is yes, then the other option would be a spray-in bed liner. Thanks in advance.

Why would it deform them? I have factory Ford plastic bed rails and an RKI 30" wide toolbox with a million pounds of tools and ...it's fine. Your plastic bed cap I supported by the metal bed.

Why not metal rail caps? I had chrome diamond plate ones on a truck with the toolbox set on top with no issues at all.

All, thanks for the replies. I am putting on the plastic Westin ones because the sales person threw them in. It had a fiberglass tonneau cover on it that caused the scratches. I guess you are right Brazosdog. It shouldn't if they fit well. I tend to dream up unrealistic problems with stuff like this. Lol

It'll be fine.

Buy some weatherstripping at hardware store with adhesive. Put under toolbox where it touches bed rails. Keeps from scratching up the plastic.