Hy,
he was using an AE gear diff but it need a lot of time and rebuilding to make it fit. He was using this long befor the official team C gear diff came out for the Tc2.
you can with make the team C gear diff fit the Tc2C with some little work.
the first difss we was using was a kyosho gear diff with AE outdrives, you have to work on the outdrives to make it fit but then it fits without any other changes
regards Tom