Abstract: A pick-up cap construction is provided which includes a novel compressible seal arrangement between the pick-up driver cab and the pick-up cap, a novel rear door construction and a novel pick-up cap holddown arrangement. The rear door construction includes a full size rear door covering the complete area from the top of the pick-up cap to the truck bed, pivoted about a horizontally extending axis disposed at the top of the pick-up cap. The pick-up cap sidewalls are attached to the pick-up truck box sidewalls by means of an extruded metal mounting rail which forms one side of a sandwich clamp construction engageable with the lower part of the cap sidewall, and which is riveted to another extruded metal profile part which serves the additional function of accommodating a mounting of a decorative profile strip to cover the connection between the cap and truck box sidewalls.