[suicideneil]

I would suggest getting a pinion puller to remove the pressed on pinion, then file a flat spot on the shaft so you can use normal pinions.

If you are going to use it as a single motor on its own in the maxx, I'd say gear it pretty much the same as you would a pair of titans that it replaces, something like 18/72 to start with, then work down on the spur or up on the pinion until you are happy or the motor starts to run too hot (outside of its most efficient gearing range).