Let me clarify. The servo
motor in the XMod is the same motor that ZipZaps use for their
drive motor. I've had my steering servo apart numerous times, and can confirm this. Of course the XMods don't use the same servo as the ZipZaps. That would be daft.
So the steering servo in an XMod consists of a ZipZap-type motor connected to a whole bunch of gears and a potentiometer.