Locking Hub Conversion Kit for Jeep XJ, YJ & TJ Dana 30 front, 5 x 5.5" bolt pattern. The Yukon worry free Spin Free Kit replaces the vulnerable and expensive factory unit bearings with tapered bearings and races. The result is not only a design which is easier and more economical to service, but one that offers significant increases in mileage per gallon. This hub kit also includes low-profile Yukon Hardcore premium locking hubs, giving you more driving selectability. This kit includes new wheel hubs, spindles, high strength Yukon 4340 Chrome-Moly outer axles, Yukon Hardcore premium locking hubs, Timken bearings, high quality seals and all hardware for installation.