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, magnificently sooty, example has a plain pulley cage stop, a black painted b-knuckle and black oxide finish on the p-knuckle. The lush chrome on my other example is nowhere to be seen.
A strange Dickensian style meets very little content...