I had mine built at
http://www.alumline.com/ I have a shorter one in the back of the truck that is realy handy. The one right behind the cab holds 2- Honda generators and a 6 gallon tank, plus gas hose for having both feed off of one tank. Rear box holds camper power cords and my tool bag. Latch on both sides with a lock on drivers side. Either side latch will open door. They make their own standard designs if you want them or they will custom build you one. Lead time on custom is about 2-3 weeks.
Here is another showing of the camper boxes. http://www.alumline.com/boxes/top-lid-boxes-rv-boxes.html I had my rear one go straight across instead of being recessed like their standard model... If you call them, they are good people to work with. I do not own or am I a part of their organization. Matter of fact, my son is a manager of the competive company here in my community.