Tamiya Hop-Up Options 22049 XV-02/TT-02 Oil Gear Differential UnitThis 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