I think someone said it before but here is what you need to do to fit the gear diff to a TC6. I am using spec r gear diff now but the process should be very similar. the diff is a little wider in the yoko so you need to narrow the diff housing by 1mm. I just mount it on my tire truer and sand it slightly. For the outdrive the hole is around 0.4mm too smaller. So just use a sanding wheel and sand it a little larger. Very simple job, took me 15min per diff.