Abstract: A wedge-shaped wheel-blocking chock for a dual wheel truck is provided with a device for preventing unauthorized, premature displacement of the chock from a wheel-blocking relationship with a set of dual wheels of the truck. In particular, the top of the block body is provided with a rigidly mounted loop, eye or the like. A rigid generally horizontal T-bar or the like is provided, having at least one slot provided vertically, transversally through its center leg. In use the T-bar, oriented sideways is slipped between the wheels of a set of dual wheels, turned flat, and the cross-bar pulled against where the backs of both wheels meet the ground. The center leg slot is dropped over the loop, eye or the like and padlocked. A security chain is also disclosed for further preventing disassociation of the chock from a wheel-blocking relationship with the truck.