They make bullet adapters for adapting between sizes if you don't want to solder new bullets. I'm using a set to adapt between a Castle MM and a Velineon 3500 motor. I didnt want to change the connectors since I will eventually sell the Velineon motor.
Not sure which you need, guessing this one - there are others made to cover most situations, so just look for the ones you need -
http://www3.towerhobbies.com/cgi-bin...?&I=LXPHD9&P=7