New from Kyosho:
New genuine Kyosho option parts for your Rock Force are now available! The new rear drive disconnect unit (DIG) will give you the advantage over the other guys and there so called crawlers. If more speed is what you are after, the high speed gear set will satisfy your need
No. RFW001 Rear Drive Disconnect Set (DIG)
No. RFW002 High Speed Worm Gear Set