Not sure what you are looking for in 'gears'
this transmission comes with a motor, designed for a crawler, meaning not built for speed
RC4WD R5 V2 1/18 Mini Transmission
this transmission should be much quicker -
ECX Transmission Set Smash also Fits Team Losi Mini T 1.0 1/18th
the 2nd one is probably along the lines of what you probably want. But for that price you could probably pick up a 1/18 roller off ebay, facebook, etc.
There are a ton of motors that will fit, look at 24mm to 28mm diameter motors