To ensure compatibility, ICON is no longer offering GM 2500HD/3500HD upper control arms as individual components. Upper control arms can only be purchased in unison with ICON shock absorbers as a complete system. The included ICON Vehicle Specific (V.S.) 2.5 Series shocks are designed and built to give your vehicle outstanding performance off-road and a smooth ride on the street. These shocks are configured specifically for each application in both length and damping tune. Like all ICON'S Shock Absorbers, V.S. 2.5 Series shocks are 100% rebuildable and 100% revalveable. The larger diameter and oil volume of ICON 2.5 IR Series shocks provide better ride quality and heat dissipation properties than the standard 2.0 Aluminum Series IR Shocks. If you are looking for a more user defined tune, consider looking into the Compression Damping Control Valve (CDC Valve) shocks.