When was the last time you serviced your knuckles? Our service kit contains all standard replacement parts including gaskets, felts, seals, washers and shims. Kit includes inner axle seals and outer felt covers. The outer felt covers are not found in other kits and are a . If you’re using your truck in the rocks you will want to replace these covers when you service the knuckles. Knuckle kit has all the parts you need to services both left and right knuckles.