Many techs find that once the plastic retainer is removed from the original equipment cam on GM trucks, the adjustment won't hold. These lock plates are designed to provide a mechanical lock for the cam bolt to the guide pin. Simply dial in the adjustment change with the original equipment cam or SPC's replacement kit #86376 and then replace the nut side cam with the lock plate. Use part number 86326 HD GM alignment pins to replace the often abused OE pins. This kit is designed for GM 2500/3500/4500 HD trucks (Upper Arm Adjustment) and the 2015 & up Chevy Colorado (Lower Arm Adjustment).