M127A2C Semitrailer, Stake, 12-ton, 4-wheel towed by an M-818 Truck, Tractor, 5 Ton 6x6. Courtesy eBay seller fuzzy_toaster.
Flat bed semitrailers are used to haul general cargo, with or without stake-supported side panels. The flat surface of the semitrailer, with no side panels, is intended for pallets, strapped loads, or containers. With the addition of stake body side panels, an open box is created that can be used for bulk cargo or loose items. When used for transporting personnel, the stake-side semitrailer is often called a cattle car.
7-Ton Semitrailer, Panel Cargo
M-118 Semitrailer, Stake, 6-ton, single axle (G-751)