Abstract: A retractable cover is provided with a panel draped over the open top of a cargo-receiving truck body, the panel having a body-surrounding flange provided with a tubular casing which receives a flexible draw-element whose terminal ends are releasably locked to the body. Stretches of the element pass from the casing into a pocketed portion of the panel and thence through a pair of eyelets. Loops on the terminal ends of the element, as well as a ring rigid to the body, receive the shackle of a padlock. In a modified form of lock the loops are unneeded. Snap fasteners secure the flange to the walls of the body.