Abstract: An attachment system attaches a structure or tonneau cover to a truck bed with side walls having stake pockets. Fastening plates are pivotally coupled to the structure or the belt rails of the tonneau cover. The plates pivotal between a first orientation in which the plates align with the stake pockets to pass therethrough, and a second orientation in which the plates rotate with respect to the first orientation to abut the stake pockets and secure the structure to the side walls of the truck bed. Tensioners can be coupled to the structure, and engage the fastening plates, to draw the fastening plates towards the structure. A cover can be removably attached to the belt rails to cover the truck bed.