As one person put it: 'Traveling at 60mph if you slam on the brakes everything in the back not bolted down will be coming at you at most of 60mph'. Under those conditions a BOB is a potentially lethal bludgeon and a toolbox has the force of a battering ram.

And using just using sheet metal screw, or bolts alone, into the metal body won't do it. You need to have large fender washers under the bolts to spread the loads and prevent the bolts from pulling through when shock loaded.

If you regularly carry loads consider installing a strong barrier. These are required for many service and delivery vehicles.