This is the Optional Two Speed Transmission Set from Tamiya.
Will work for the gas TGX kits from Tamiya.

FEATURES: Two speed transmission kit, plastic gears, ball bearings,
clutch shoes, one way bearing, etc.

INCLUDES: Two black plastic gears, 51 tooth spur gear, 47 tooth spur
One aluminum 6mm one-way bearing
Two aluminum two speed pinions gears
Aluminum clutch bell
One 2-speed shaft, one aluminum long pilot shaft
One 2nd gear hub
Black plastic rotor hub
One two piece clutch shoe
One metal parts bag
Instructions on back of cardboard

REQUIRES: Nothing

COMMENTS: This is a complete two-speed transmission. These parts are not
sold seperately.