In reality there are very few screws attaching the actual wall panels to the van metal walls (top & bottom). The walls are attached to the back of the cabinets with L-brackets or via the window boxes. The cabinets are securely attached thru the floor.
Cabinet sides are bolted down through the vanís steel floor using 8 to 12 special steel ďLĒ plates. Cabinets are also secured to the vanís sides, and other appropriate points."