parts for motor vehicles, namely, gear boxes; transmissions; differentials; axle kits comprising front and rear axle shafts and axles, half shafts and drive shafts; steering racks and pinions; vernier and duplex timing gears; drive gears; and gearing and gear kits comprised of gear shafts, gears and pinions for driving gear boxes; gear box casings, gear levers and gear shifts; and engine cylinder blocks