Thank you for the feedback. I may need to pick-up some hardened pinion gears. Is there additional noise when using a steel spur with a steel pinion?

FYI - I removed about 0.5 to 1mm of material from the diff side of the motor mount. The material that was removed started with a diameter 2mm larger than the bearing opening and went to a diameter slightly larger than the teeth on a 46-tooth Kyosho spur gear. This allows for the clearance of the counter sunk diff screws and the spur gear teeth. Due to the offset of the Kyosho gear those were the only two conflicting areas that needed additional clearance.

Thanks again for the feedback.