Ricardo is one of the biggest and best gearbox manufacturers in the world. They also make gearboxes for Jaguar, F1 cars and more.
Ford did not cut any corners on the driveline of the GT. As we've all seen the engine is nearly bullet proof on these cars. They went direct to AP Racing for the clutch who make clutches for most of the Formula One teams, WRC rally cars, indy cars, etc.