Custom diff:
http://www.rc-monster.com/proddetail...rod=rcmflmrvdf
Stock tranny is pretty strong, and the 9L doesnt produce quite as much torque as an XL motor, so it
should be fine. If you intend to mainly race, then I would say leave it unlocked, but if you want to bash more, then locking the tranny in 2nd is a good idea (very simple) so you can use the motor for braking+reverse, otherwise you will need to keep the mechanical brakes fitted, and probably disable reverse on the esc since the reverse gears are very weak.