I built a big truck gun box for long road trips so we could get more stuff in the back of the truck without just having a huge pile. It works real well, you can fit a ton of guns in it and a lot of gear on top. The top is pretty heavy duty, I have had 5-6 ammo cans full of ammo on top before in addition to other hunting gear. Free to a good home, even if you just want to burn it.
The box is about 4' wide and 5.5' deep, it should fit in any modern pickup. If you have one of those super short 5.5' beds it may be tight. Must be picked up at my warehouse in Brooklyn Park.
I got a new truck this summer and am going to make a new improved version for this truck.