Just a follow up. Not much as been mentioned about the pinion gear going onto the RZ350. I bought the 10T one recommended only ruining it heating up thinking I could slide it on hot. The brass got too hot and deformed ruining it.

In desparation, I 'pryed' off the pinion from the cheasy brushed motor with two screwdrivers and went to fit it onto the RZ350 only to find it slid on perfectly. Now I was out of luck until perusing RCUniverse and finding that a certain LocTite would bond the pinion to the shaft. Only problem was no one had the stuff.

I did find what worked at Napa Auto Parts. It's a Permatex Sleeve/Cylinder bonding stuff. Cost me 8 bux but it worked perfectly. In fact, as I was sliding the pinion on the shaft I could feel it locking the gear to the shaft. Must be liquid weld because I gave it the 24 hrs drying time and it works perfectly.