Just as the Schwinn GT510 was supposedly an improvement on the Schwinn GT500, so the Schwinn GT515 was supposedly an improvement on the Schwinn GT510. And, remarkably, the GT515 was both the very last derailleur to bear the Schwinn name and also the sixth ‘improvement’ of this design over nearly two decades - and guess what - it is virtually identical to the 1964 Schwinn Sprint.
This particular example dates from 1983, 25 years after the first Huret Allvit, and about 15 years since this design was obsolescent. It even has the ‘matte chrome’ finish that typifies Sachs-Huret’s restyling of the old Huret designs.
Dead before it was born.