Three-inch diameter Currie Johnny Joints were welded in place on the end of the radius arms. The Johnny Joints use urethane bushings to encase the heat-treated ball center, so they run quietly and are shock absorbent. An added benefit is that the urethane bushings are inexpensive to replace when they're worn. The Johnny Joint urethane bushings on this truck are holding up great. The first set has yet to wear out.