Drive axle assemblies for vehicles and component parts thereof including axle shafts, differential mechanisms, worms and gears, drive axle housings; multi-speed drive axles and component parts thereof; tandem axle assemblies for vehicles, bogies and limbers; and drive transmission mechanisms for vehicles including clutches, speed change gearing, torque converters, transfer cases, torque dividers and gear boxes and component parts thereof and universal joints; dirigible and trailer axle assemblies and component parts thereof; steering elements; wheels and hubs; brake assemblies and braking systems for vehicles and component parts thereof and boosters therefor; springs for vehicles, including leaf springs