Campagnolo Nuovo Gran Sport (3500 3rd style) derailleur

In the years up to 1973 Campagnolo offered a derailleur range that went, from the top, Nuovo Record, Record, some Valentino or other and then some kind of Sport single pulley model. With the arrival of the Super Record derailleur it was clearly time for the old bronze and steel Record to depart this mortal coil and be replaced by a largely aluminium model - and this is it, the Campagnolo Nuovo Gran Sport.

There are various legends about the Nuovo Gran Sport, some said it did not shift 'nearly as well' as a Nuovo Record, others said that it could happily handle a 28 tooth cog whereas it was best to limit a Nuovo Record to 26 teeth, etc. etc.. To my eye, and as measured by my trusty Vernier calliper, it had exactly the same geometry as the Nuovo Record - and so I have always thought these legends were nonsense. Indeed one of the sales points of the Nuovo Gran Sport was that it was an ideal derailleur to fit to your winter bike as it would shift exactly like the Nuovo or Super Record on your good, race bike. Of course many winter bikes were fitted with that old, left-over Nuovo Record that your cycling club pal had in his shed from the time that he upgraded to Super Record...

The Campagnolo Nuovo Gran Sport was a modest, honest piece of kit that had only one downside. It was priced considerably above much better derailleurs from SunTour and Shimano, and it did not have the 'glow of ultimateness' that allowed people to want to pay the price premium for a Nuovo Record or Super Record. Modesty does not sit easily with hype and bling.

I believe that this is a later example of a Campagnolo Nuovo Gran Sport, dating from 1983 or shortly thereafter. Some of its distinguishing features are:

The b-knuckle has no lettering on it.
The main hex bolts at each knuckle have concave heads and no lettering.
The parallelogram spring is mounted on the inner p-knuckle parallelogram pivot.
The cable clamp bolt has a concave head.

One of the the laws of nature is that there is always someone out there who knows more about Campagnolo than you do. If you are that person, please feel free to let me know about any errors or omissions!