Abstract: In association with a conventional truck box, trailer or enclosure having a rear door communicating with the sides, top and bottom of the enclosure, a hollow holding sleeve is secured to the inside of the door with a securing plate fastened to one side of the enclosure and a locking plate to the other side. The plates include apertures which are aligned with the hollow holding sleeve and the locking plate communicates with the exterior of the enclosure. A locking bar extends through the aperture of the locking plate and the hollow holding sleeve and into the aperture of the securing plate. A locking device is mounted onto the locking plate to securely hold the locking bar in place. When the locking bar is in place, movement of the door is prohibited and the door can not be opened.