Replace worn rear knuckle cross axis ball joints on the IRS Mustang Cobra with xAxis joints from SPC Performance. SPC's cross axis ball joints feature highly polished electroless nickel plated balls, corrosion and wear resistant moly impregnated nylon races, and dust boots to keep contaminants out ensure long life. xAxis Joints come pre - greased and are designed to be maintenance free. This kit includes four (4) xAxis joints and press tool adapters to service a complete rear end. Use press tool 40940 or similar. Just need to replace one bushing Order SPC part number 15645. California Residents WARNING