Originally Posted by
cyclotoine
I noticed that too and assume it is because it is easier to work in steel. The pivot bolt has been cut and threaded and a new part has been made that screws into the pivot bolt to sandwich the stop. That piece threads into the drop-out. I have to say, the design is so elegant that I do not immediately think the seller is wrong. I am open to the possibility that it may be a factory prototype or even just an R&D piece done as a test that was never even considered a prototype for any real production. Simply, a "how are we going to incorporate a and adjustable parallelogram angle" type of exercise done in the factory machine shop. It's possible.
For me, the assemblage is too "swiss watch" delicate and complicated, it is unique, but there is no evidence that it was fabricated in house by Campagnolo. Maybe produced to a special request of a national team (for some reason). Big Maybe. If one looks up the patent applications of Campagnolo in the early 80's they were churning through the ideas most likely to find an alternative to the Suntour slant parallelogram design that they could patent. Go through those patent applications and lots of derailleur designs that never saw the light of day can be found, but nothing like this fabrication.