For 1968 SunTour developed its 1965 SunTour Competition model into this - the first SunTour V. The knuckles and pulley cage plates were now aluminium, the pulley cage spring assembly was tidied up and the major pivot points got arty ten-sided bolt heads with spiffing SunTour logos. A beautiful piece of work.
Most importantly, SunTour managed to get an aluminium, slant parallelogram derailleur, weighing only 218g, into the consumers greedy hands for an amazingly low price. It was an instant success.
Another of my ‘derailleurs that changed the world’.