HPI Savage owners can now get a fully assembled version of the HPI 4 Bevel Gear Differential Conversion Set for their trucks. The 4 gear conversion is a popular upgrade, especially for heavy-duty driving and high horsepower applications. Now HPI offers a factory assembled set that is a direct replacement for the stock diff, making installation faster and easier. The extra gears decrease the stress on the drivetrain for longer gear life and less maintenance. Each package contains everything needed to upgrade one differential.