I just purchased a Ryobi 31cc short shaft & I am going to machine my own parts but I'm getting confused as how exactly the crank shaft adapto is supposed to work. One set of instruction talks about modifications to the stock flywheel nut but I can't figure out how to use that nut & install a extension with the prop hub adaptor. It seems like it would be easier to machine the flywheel nut, shaft extension, & prop hub adaptor into one piece. And if so, how long do you make the adaptor from the face of the flywheel to the back of the prop?