ReadyLIFT OEM-style rear block kits are available for model specific applications. These Rear Block Kits include two (2) 3" Rear Blocks, four (4) E-Coated U-Bolts, eight (8) Nuts and Washers and will safely lift the rear of your truck an additional 1" to 3" depending on the application. Based on OEM designs and never made out of light weight extrusions, our 3" GM Blocks are made from cast iron and have anti-rotation ears built-in. Fits 1999-2021 classic and current body style 6-lug model GM trucks. Models with 1.25" OEM blocks will want to take advantage of the additional 1.75" of lift for towing and hauling, particularly when using a front leveling kit. 1999-2006 4WD trucks will replace the factory 2" block for 1" of additional lift. This kit eliminates the dangers of having to stack blocks which may be illegal in some states. ReadyLIFT Block Kits will put a slight rake back in your truck for hauling or towing and are designed to work in concert with your ReadyLIFT Suspension Leveling Kit. Like all ReadyLIFT products, these block kits come with our Lifetime Warranty. Installation time is approximately 1.8 hours. Note: 2019-UP models may need to trim off excess bolt length after installation. NOTE: This GM 1500 kit is NOT COMPATIBLE with vehicles equipped with rear composite mono-leaf springs. The mono-leaf is easily identifiable the U-bolt is round/circular around the top of the leaf spring. This kit only works with vehicle equipped with traditional steel leaf springs identified by square U-bolts.