QSA 1" - 3" Keys + 2" Blocks + U-Bolts - Compatible 2000-2010 CHEVY GMC 1500HD 2500HD 3500HD Silverado Sierra Fits RPO Codes FK2-FK3, FF6-FF7, FF8-FF9 Codes in Glove box! See Description Below for applications (2000 - 2010 Chevy / GMC HEAVY DUTY MODELS) Includes: Heavy Duty Forged Torsion Keys (L+R), 2" Lift Blocks, AND U-bolts Allows for leveling (lifting) the Front of Your Vehicle Between 1" - 3" in the front and 2" in the rear. However, we dont recommend going above 2.0" in the front. Torsion keys Have High Quality Powder Coated Finish to Protect from Rust Blocks are tapered to correct for pinion angle