Zeus Gran Sport (1965? version) derailleur

The Zeus Gran Sport began life as an unrepentantly blatant Spanish copy of the - you guessed it - fashionably Italian Campagnolo Gran Sport. The exact history is a little unclear to me, but may go something like this:

As early a 1952 Nicholás Arregui Gallastegui had taken out a Spanish patent on a near exact copy of a 1950 Campagnolo Gran Sport. I am not sure whether this particular Zeus model ever went into production.
I believe that during the later 1950s (perhaps 1958?) Zeus manufactured rough and ready copies of the 1953 Campagnolo Gran Sport.
By 1961 the Zeus Gran Sport had become more exactly made and better finished, and was now a very creditable copy of the aforementioned 1953 Campagnolo Gran Sport.
In 1963 Campagnolo released the Record derailleur with an offset pulley cage, albeit with steel pulley cage plates.
Perhaps in 1965 Zeus responded by upgrading the steel Gran Sport to also have an offset pulley cage. Innovatively, the new pulley cage plates were aluminium, although the parallelogram remained steel. But, unlike Campagnolo, Zeus retained the name 'Zeus Gran Sport'.
In 1966 Campagnolo released the Nuovo Record derailleur. This was an all-aluminium model and was strikingly light in weight.
Possibly in 1967 Zeus responded again, this time slightly feebly, by merely replacing the Zeus Gran Sport's steel pulley wheels with lighter plastic ones. These were disctinctive because they had no dust seal washers.
In 1969 Harm Ottenbros won the World Road Race Championship riding a Zeus Gran Sport - which was then rechristened as a 'Zeus Criterium 69' in honour of his ill-fated achievement.

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Zeus mysteriously reused the Gran Sport name from possibly 1979 to 1982. This beguiling derailleur had the model number 22200 and was startlingly cheap. But I do not know exactly what it was.

My guess is that this Zeus Gran Sport dates from about 1965. It has an aluminium, offset, pulley cage with round steel pulleys.