Revolution Gear and Axle GM 12-Bolt Truck Master Overhaul Kits come with all the necessary parts to ensure your differential job is a success. Revolution Master Overhaul Kits come with top quality Timken Bearings and National seals. Our Kits also include: Pinion seal, Pinion Shims, Carrier Shims, Pinion Nut, Gasket or Sealant, Preload Shims or Crush Sleeve, Ring Gear Bolts, Gear Marking Compound and Loctite.