Abstract: An enclosure with fittings removably coupling enclosure members with the fittings being formed from plate stock. Insert fittings each include a leg member insertable into a socket fitting having a triangularly shaped socket in which the leg member is received in a snug manner. An apex portion of the socket fitting is slidably received in an elongate slot of the insert fitting.

Abstract: An enclosure for installation about the load carrying area of a truck with the enclosure includes removable corner posts for inserted engagement with truck structure. Enclosure side and end rails extend between the corner posts and are adapted for removable, rested engagement with the corner posts to permit convenient installation and removal of the rails. Multiple rows of sockets on each corner post receive pins carried at and offset from the ends of each rail member. The pins are horizontally adjustable relative to the rail member to facilitate socket engagement. A modified form of the enclosure includes corner post fittings of right angular shape each apertured for purposes of corner post attachment. Sockets on the post fittings receive the pins of rail carried fittings to enable part installation on the corner post in a detachable manner.