SUPERLIFT Rear Block Kits include the same blocks used with our Lift Kits. They are listed specifically as Cast Iron or Fabricated Steel. Most blocks are tapered to improve drive shaft angle/alignment. U-Bolts are manufactured from low alloy, high strength steel. Thread type is National Fine Class 2A. U-bolts come in either anti-corrosion zinc or black e-coat finish. Included are (2) Lift Blocks, (4) U-Bolts, (8) size specific long nuts and (8) phosphate coated, heat treated, extra thick washers (Block kits are not Intended for use on the Front of any vehicle – It’s illegal and highly unsafe).