What's the difference between all those gears?
 

I noticed that there is a lot of selections when looking at gears.What's the difference between the 3.42,3.73,and 4.10?What brand do you guys trust when buying your mods?

Thnaks

The higher the number is, the shorter the gear, hence the quicker acceleration but lower top speed.

exaclty what Supermario said. The shorter the gear, the quicker the acceleration but lower top speed while the taller gears will have weaker acceleration but higher top speed(too a limit with all other typical variables being being equal). The gear ratio numbers are means to identify the number of rotations the pinion gear makes in relation to the number of rotations the ring gear makes(how many times the rear wheels turn). For instance, 3.42:1 means that for every 3.42 turns of the pinion gear, the ring gear will only do one full turn causing the wheels to turn once. To get the gear ratio, you divide the number of teethe on the ring gear by the number of teethe on the pinion gear.