This is what HPI says about this kit... Savage owners can now get a 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 precision factory manufactured set that is a direct replacement for the stock gears. 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, including strengthened & notched gear shafts, and revised gears that are hardened for extra durability. This will be a very popular option part for Savage owners!

PLEASE NOTE: This kit will upgrade 1 Savage differential (front or rear). In order to upgrade both differentials on your Savage, you will need to purchase 2 kits.