The UMI P/N 2999 adds the finishing touch to allow full articulation of the GM 4-link rear suspension. By using 2999 and either Roto-Joints or rod ends in the other six locations, your 4-link will move bind-free whether it be autocross transition, road race cornering or just back road corner carving. These Roto-Joints install with a gentle press fit and are retained by a spiral retaining ring. The 6061-T6 aluminum housing is pre-greased with Synco Super Lube and will provide smooth motion for years to come. 100% manufactured in Philipsburg, PA-USA.