Abstract: A utility box is mounted to a truck box without piercing the wall of the truck box. A J-bolt extends through a neoprene gasket, a washer and a back-up plate to clamp the back wall of the utility box to the front rail of a truck box. For mounting within a bedliner, the utility box is held against vertical displacement by stair stepped brackets which are bolted to the utility box to extend beneath the truck side rails. The upper faces of the stair steps are designed to interface with a variety of truck models of varying widths. When mounted in a truck box with an over-the-rail bedliner, a bolt is positioned inside the utility box and such that a shank passes through the wall of the utility box and the side wall of the liner. A spacer is positioned on the shank between the utility box wall and the wall of the liner. A collapsible nut mounted or the shank passes partway through the liner wall.