UMI Performance 65-66 GM B-Body Tubular Upper Control Arm/Trailing ArmRear control arms are one of the most important suspension modifications that can be done to your GM vehicle. Stock control arms are on the borderline of "junk", bushing deflection and rusting weak stamped material add for traction loss and poor handling ability. The included high quality polyurethane bushings are an excellent improvement over the OEM rubber bushings, while adding ride improvements they also work excellent to reduce traction loss.