Thanks for all the tips, your a real help. i have about 10 world scale trucks and cars. from nitro thunder kings to desert thunder and electric thunder kings. plus i have found and bought alot of parts on ebay for them. is the diff a direct fit or does it need to be tweeked to fit. also i had forgotten this so maybe you know is the spur gear metric or std pitch. i can't remember. i see you used ofna to replace the spur and i have tons of ofna parts. check out my gallery pictures and you can see some of my mrc kits along with my other stuff. thanks, Randy