Bonjour Doug,
If you refer to my D10, replacing the initial on too toght, the coupling system is now what we call "TOC" in France, acronym I do not know furthermore.
One part is male and the second female, the first has 2 plugs, the second 2 slots at 180 °.
the clearance in the adjustment allows a small offset between the machine and the propeller shaft.
I hope you see it better there :