Superlift rear block kits help distribute the weight of your cargo and improve the towing performance of your truck. They'll also give your rear a little lift to bring it back to the proper ride height. Superlift's block kits include two cast iron lift blocks and four U-bolts with factory type Hi-nuts and flat washers. The blocks are cast from Class 30 Gray Iron, the same material used by vehicle manufacturers for their spacer blocks. Our U-bolts are manufactured from low allow, high strength steel. The anti-corrosion finish is either Zinc or E-coat