1999-2006 Silverado/Sierra 1500 Classic 2WD 1999-2006 Silverado/Sierra 1500 Classic 4WD Maxtrac Suspension's rear shock extenders are designed to provide extreme stability for a lowered vehicle. When brand new shocks aren't required or needed, these extenders lower the mount of the current setup, and adjusting the angle of the shock to its correct angle. For the 99-06 Silverado and Sierra trucks, when lowering the rear of the vehicle 4-6", its a great idea to use a shock extender on the passenger side shock, as lowering the vehicle puts the shock in a slightly horizontal angle, compromising the shocks ability to properly dampen the ride. This extender fixes that issue, the driver side shock maintains an ok vertical orientation when lowered to these heights, so a shock extension isn't needed. SPECIFICATIONS 100% Bolt On Installation Uses existing shocks Corrects shock angle for a lowered vehicle Passenger Side Use DIMENSIONS: 9x4x3