You should get these gears instead of the factory replacement ones. I have went through 3 sets of gears. They come with every thing that you need excep the grease. These are the ones that come with the MT 2 SS kit.
HPI Part number 86336
[link=http://www.hpiracing.com/buyhpi.htm]86336 Gears[/link]
Hear they are at towerhobbies
[link]http://www2.towerhobbies.com/cgi-bin/WTI0001P?&I=LXJYM2[/link]
Here are the cheap factory replacement ones
[link]http://www2.towerhobbies.com/cgi-bin/WTI0001P?&I=LXTB48[/link]