My son crashed the c-hub on his tamiya neo fighter, so I took a short measure and designed the c-hub by myself, to get the car back on the track. The holes have to be smoothed with a 3mm drill or better with a 3mm reamer. The arrow points to the upper side. It fits to tamiya DT-03-chassis and similar.
v2 has longer "arms" - like the GPM aluminum parts.