Bearing spacers for use with TJ Unit Bearings and WJ knuckles These weld in spacers are needed when using TJ unit bearings with WJ knuckles in order to properly align the u-joint with the ball joint pivot centerline. They also help with proper brake rotor alignment. Sold in Pairs. Please note, these spacers must be welded in place and should only be installed by a qualified professional. We accept no resposiblity for failure to properly install.