This is a new gear differential unit for use on the XV-02 and TT-02 chassis. When using it on the TT-02 chassis, it allows you to tune the differential action, for the front and rear, with the use of different viscosity oils. When using it on the XV-02, you can use it not only for the front and rear diffs, but also as a center oil-filled diff unit, which will give you even more tuning options! When using as a center oil-filled diff unit, on the XV-02 chassis, make sure to use with Item 22050 (06 Module Spur Gear 70T). Differential Joints x2 Gear Differential Ring Gear (39T) x1 Bevel Pinion Gear (for 39T gear) x1 Differential Case x1 Gasket x1 GV Gears x2 2.8x23.4mm Cross Shafts x2 2x8mm Countersunk Hex Head Screws x4 5mm O-Rings x2 5x15.2x0.2mm Shims x2 5x7x0.1mm Shims x2 3x5x0.1mm Shims x4 1280 Ball Bearings x2 Silicone Oil #3000 Compatible with XV-02 and TT-02 chassis cars.