Can't recall,...look up their website, but mine is #6913-02 is the 23 spline unit for 130 tooth flywheel.

I spoke to their tech line the other day, because my disks fit pretty loose on the input shaft. The tech person is the guy that designed this clutch. He said it's fine and is supposed to be very loose to give great disengagement features, and not to worry. He has the same clutch in his 57 chevy with big hp, and he can push this clutch in with his hand very easily, no effort. He also said it doesn't have the ON / OFF feature. It is a great STREET clutch that can take the hp at the track. It's not a RACE clutch.