If it is the Delta brand tool box sold by Tractor Supply (at least that is what it looks like in the picture) the lid isn't stout enough. Otherwise, yeah, that might work. Personally, I'd try putting the rear up since it is lighter.

 

front or back, feels the same... LOL

 

Even though I have a 6.5 bed, if I get a tool box it will be a fender box and not one behind the cab...I know they're smaller but I hate giving up even 18" of bed space...