a. a load structure comprising frame walls and inner bracing, and including a plurality of flanges, each of said plurality of flanges having an aperture disposed therethrough, said load structure also having at least two pivot bearings; and

b. a bearing plate having a plurality of fasteners extending from an underside of said bearing plate disposed at locations corresponding to the disposition of said apertures configured to permit removable attachment of said bearing plate to said load structure and plurality of ridges disposed upon the underside to form a seat for said frame walls, and a plurality of ribs extending longitudinally along the underside of said bearing plate from a rearward side of said bearing plate to cross the outermost of said ridges, said ribs conforming to the outer wall of said load structure when attached thereto.