OTC 6695 Axle Shaft Seal Installer for Ford 1998-2004 F-250/350/450/550 Works on 1998-2004 Ford F-250 F-350 F-450 and F-550 4X4s having the vacuum-operated front axle Correctly installs the seal onto the axle shaft and into the wheel knuckle Prevents front hub vacuum leaks that would cause the 4WD to not engage