X Joint 07-18 Jeep Wrangler UJ Rubicon Dana 44. The new heavy-duty X-Joints are a direct replacement for the factory U-joints and are manufactured from 8620 case hardened alloy steel. Alloy USA has incorporated a number of design features to ensure the joints stand up to the stresses of off-roading. Each of the X-Joint’s forged bearing caps feature an individual grease Zerk fitting for quick, easy and complete lubrication. In addition, triple ridge seals help keep out dirt and contaminants to maximize joint life. Each X-Joint comes complete with four 360-degree retaining clips, four 180-degree retaining clips and four grease Zerk fittings.