Silverado Sierra Lift Kit 3" Rear Lift Steel Blocks + Extra Long 12" U Bolts FITMENT: 1999 - 2018 Silverado Sierra 1500 4WD/2WD; Does not fit models with spring overloads CONTENTS: 2 US certified tapered steel lift blocks with 4 OEM grade steel square bend u-bolts, hi-nuts and extra thick washers TECHNICAL NOTES: Install the tallest ends of tapered rear blocks to the rear of the vehicle; Retighten u-bolts after the first 500 miles BENEFITS: American Automotive steel lift blocks are stronger than aluminum. They are designed to increase rear load and towing capacity. American blocks absorb noise and vibrations, and are tapered for perfect pinion alignment. Made for maximum u bolt clamp force with an even distribution of pressure, American axle u bolts eliminate flexing and provide the strength to maintain original vehicle handling. 1999 - 2018 Silverado Sierra 1500 2WD/4WD; Does not fit models with spring overloads 4 x certified carbon steel square leaf spring axle u-bolts. hi-nuts and washers 2 x carbon steel tapered lift blocks Instructions Length:12&#034; x Width: 2.5&#034; x  9/16&#034; Thread Pitch 5&#034; thread can be cut down to fit other applications 3&#034; Tall x 2.5&#039; Wide x 5&#034; Long 9/16 pin