G'day as was stated earlier grab one of the pto extenders with the button, or if you want check out the bare co site they have a few different size triangle tubes to choose from. Kco you are right about the shaft only going one way but this is done by a flat on the top of one of the 'flutes' and you are right it is called "phasing" and it is so the yokes are lined up correctly if they aeren't then you will get horrible vibration and the cross will detroy itself in no time.
Jon