Planetary Modeling Help

[DampRobot]

I'm currently trying to do a project based on the P-80 BaneBots planetary, and need some help with modeling it. I would like some help with modeling the ring gear, either in Inventor or Solidworks. Ideally, this model would be designed with the Design Accelerator or the Solidworks equivalent in such a way that I could modify teeth numbers, diametral pitch, etc. without re-modeling the part. I'm hoping I could use this model in a dynamic simulation.2

[Peck]

This may help:
http://www.firstcadlibrary.com/pages/motors.asp
some of the cad models have the gears, some just have the end shafts set for the correct ratio, and some have no gear mates at all.