Now they come with metal gears though they do require a larger motor to help them run, the kit is by means for beginners it requires all the resin and metal parts cleaning up as in removing all the pour plugs and casting plugs also when you work on the axles you need to mark all the parts as being specific to that axle and that end of the axle they won’t go together in a week you may also still need to tap all the holes as the self-tapping screw idea is totally useless and you will find yourself either breaking the screws or striping the head, parts that don’t come with the kit that you will need to get it running,
Large motor
Servo
Speed controller
Battery
And a rather large portion of patience.
http://www.rcuniverse.com/forum/m_8466034/tm.htm