RAILROAD FREIGHT CAR STRUCTURES, NAMELY, DOORS, ENDS, ROOFS, FLOORING, [ AND LINERS; CENTER PINS, BOLSTER PARTS, ] COUPLER CENTERING DEVICES, AND UNCOUPLING LEVERS AND PARTS THEREFOR; SLOPE SHEETS AND CHUTES, STAKES, SILLS, STEPS, BRACKETS, POSTS, [ STRIKERS, ] FASTENERS, TOP SIDE PLATES, BRIDGE PLATES, WEAR PLATES, AND REINFORCEMENT PLATES; AND SPRINGS, ALL OF RAILROAD CAR CONSTRUCTION, READY FOR INSTALLATION