Brian's website shows that if the gear was originally 7.2 mm then the pitch would be mod 0.6. That's 48 pitch isn't it? I think that might be it.
Maybe look in the slot cars area?
http://www.ncphobbies.com/arp-1/24-g.../arp4810strts/
Or could this fit?
http://store.rc4wd.com/10-Tooth-48-P...ear_p_597.html
Or maybe find something on ebay?
http://cgi.ebay.com/Losi-Night-Crawl...item20b6214e1b