Just got a new Castle mmp and 3800 combo for my sc10. Motor has 5mm shaft. Robinson is now making the pinion gears for this set up. My stock Reedy 3300 came with a 87 tooth spur and a 18 tooth pinion. How many teeth on the pinion gear is everyone using on their Castle 3800 motor and 87 tooth spur gear? Castle docs suggest 14-18 teeth for a 2WD sc10. Robinson comes in odd numbers so I am thinking 17 or 19 or???? Thanks