This advert gives a better view of the mystery derailleur featured in the Sanko advert of September 1966. Again, I guess that it might be the legendary (mythical?) Sanko Procyon PV-II. Some sources claim that this has plastic parallelogram plates - although, to my jaundiced eye, they look like metal pressings (rather than the machined castings used in the Sanko Procyon PV-I)

• Publisher: New Cycling
• Country: Japan
• Date: October 1966
• Derailleur brands: Sanko
• Derailleurs: Sanko Procyon PV-II?