Yokomo make one for the tc4 which I know Stormer Hobbies sell. There was someone on here who was selling ones he made himself which looked high quality (search for 'carbon fibre shafts for touring cars' or something similar). I think he stopped making them for a bit, but maybe he has some left in stock. I think team bomber racing made one too, but I dont know about where you can get that...
Hope some of that might help you,