CST Fabricated Lift Blocks are the perfect solution if you're looking to raise the rear of your truck. You'll quickly and safely add 4" of rear lift to your truck. Installation takes approx. 1 hour and is fairly simple. In order to install these lift blocks, you will need longer U-Bolts. If you don't already have longer U-Bolts, you'll need to order a set above for an additional charge. The part number for this item is CST Suspension CSB-C14-4 and it fits 1999-2006 Chevy Silverado, GMC Sierra (1500 2WD Standard Cab, Extended Cab Models). Does not fit the crew cab.