here is the link for the ring gear I should use. but the thing is just so ecpensive. I think I will strip a cupple of stock gears off first.

http://www2.towerhobbies.com/cgi-bin...?&I=LXTB54&P=Z

and here is the stock replacement http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXTB48

seems a little pricy. and there is no way that I could make that.