Abstract: A multi-purpose fairing for mounting behind the cab body or sleeper box side extensions between the floor line and the roof line and outside the arc of the trailer when mounted to the fifth wheel. The multi-purpose fairing converts space behind the truck cab into a usable storage volume and includes three skins acting as a structural frame with a sealed top cap, a sealed bottom, utility shelves, and a door or doors allowing access to the interior storage space. The skins are supported by extrusions designed for multiple functions including an integrated hand rail, a T-slot for a rubber corner bumper, and joggle locks to lock the skins into position.