2014 Bed Liner Questions

Trying to figure how my 2014 Tacoma bed liner is fastened and what is actually underneath it. I am building a slide out box and would like to secure the box floor to the bed liner using what looks like large galvanized metal screws or bolts holding the liner to the bed. But I can't find the other end of the bolts on the underside of the bed. (Nor can I loosen them). So....(1) what are those bolts, (2) do they have nuts somewhere in the underside, and (3) what is under the liner? Steel, plastic? Thanks for thoughts and ideas?

 

There is no liner second gen tacomas have a composite bed with steel fenders bolted on the sides. The large bolts you see on the bed floor are the bolts that hold the bed on and they thread into the frame if I'm not mistaken.

 

x2. The bedliner you are referencing to is the actual truck composite bed bolted to the frame.

 

Thanks guys for the info. I suspected the bed was something other than a lined steel bed after crawling around underneath but was not told that at the dealer. I'll come up with another way to secure the case to the bed. Thanks.