I cant help with the parts really. I have not really bothered with my madbull since I cannibalised it for my yokomo.

I can tell you that the 11t motor will overheat VERY quickly in a madbull - the bull is geared for a 27t stock motor, and due to the way the motor is mounted you cant gear it down enough (at all?) to run such a low turn motor.

I was running a 23x2 and that was getting dangerously hot! - 11t will probably be suicide.

your best hopup route for the Bull would be a bearing kit all round - that made the biggest difference to my bulls performance.

good luck - try tamiyaclub.com - like I said they love their tamiyas there and can probably name a few specialist suppliers. As I recall tamiya sell their parts by the bag, so you might have to buy a whole gearbox, just to get the c3 motor cover, but there were a few suppliers that sold open bags.

Ahab.