Cognito 3 Degree Rear Pinion Angle Shim Kit For 99-18 Silverado/Sierra 1500 2WD/4WD / 01-10 Silverado/Sierra 2500/3500 2WD/4WDUsed with short wheel base trucks with tall lift where no tapered blocks were available. Includes 2 shims and 2 center pins to bolt shims to leaf packs. Use for single cab trucks or extended cab short bed, with 4 6 Inch rear lift that has no pinion angle change such as spring Only or straight block. Details: 3 Degree Rear Pinion Angle Shim Kit for 99 18 Silverado Sierra 1500 Trucks Angle Degree: 3 Degrees Drive: 2WD 4WD Location: Rear Compatibility