You don't need heat and you don't have to worry about snapping off the weld on the nuts. If you need a picture of the bolt assembly here is a picture. The large black body lift spacer may not be on your truck though.

 

One final question-How do you know if the bed is loose and needs tightening? My wife thinks so.Says it rattles to much.

 

I just say to use heat because my box bolts don't look that new. I live in a city where we put more sand on the street in the winter than we do concrete in the summer :P

 

Thanks guys.I think I know enough now,when I get ready to mess with it. I'm not really sure if I need to tighten them or not.Guess it wouldn't hurt.May wait till spring now.Can only work outside.

 

Try putting 100 or so pounds into each corner of the bed. If the rattle is still there, then the bed isnt loose

 

Double check the spare tire if it is still under the box .... mine was loose and drove me a little crazier until I found it.