You might do a search for Jack Chrisman or Chrisman transmission. I know they carry some of the higher end transmissions and might be able to help you. There is another one that I can't remember the name of off the top of my head. I will look through my papers tomorrow and find the name. Good Luck
I think Bruce Couture at Modern Drivelines is doing the G-force stuff now. He is a super nice guy and builds quality stuff. http://www.moderndriveline.com/