Synchros?

They are the where Honda of USA sends transmissions to get repaired/rebuilt. I called them when i repleaced my 5th gear syncro and they did not have the parts. They were the upgraded Carbon syncros… I was able to find Orginal “yellow metal” sycros from, http://www.hondaautomotiveparts.com/

They are a good place to get stuff from.

Good luck.