This generation of Gamabato Sport is an 'inexpensive', functional, spot-welded, pressed steel, object that can only be described as crude and ugly. It shares a lot of design features with a Spanish derailleur called the Triplex Sport - which dates from 1974.
As with most of my Gambato derailleurs, I have not real evidence for dates.
This example has a threaded pulley cage stop and, rather glamorous, chromed, parallelogram plates.
The kind of derailleur that Cadmium plating was created for...