A rear deck post assembly is provided for reinforcing a cargo bed of a utility vehicle. The assembly includes a first deck mount coupled to a vehicle frame, and a first rear deck post coupled to the first deck mount. A second deck mount is provided coupled to the vehicle frame and spaced apart from the first deck mount. A second rear deck post is coupled to the second deck mount. A deck sill component is provided longitudinally extending between the first deck post and the second deck post. Deck bolts may be used to couple the deck sill component, deck mounts, and deck posts to the vehicle frame. The first and second deck mounts and deck posts may be a cast aluminum alloy, a cast magnesium alloy, or a fiber reinforced composite material.