This a box I purchased at Tractor Supply to fit flush the the bed of a pickup. It has an offset hinged lid, so it can be mounted flush to a wall. The dimensions are 48" long, 20" deep. Maybe 18" deep, (didn't measure that one). I cut a piece of 1/2" marine plywood the size of the floor of the box, and set the tool box on the plywood. This is to prevent dents in the floor in case something gets dropped in. I used standard bolts with nylon lock nuts. Under the tongue is a standard "U" bolt bracket. It has travels over 2500 miles without a problem. I also mounted a sewer hose carrier to the box for an extra sewer hose.
