[racer]

In 1975, the 911S was the standard model. Some say it used to stand for "super". Pre '75 there were various 911 models.. the 911L, the 911S and also the 911T and 911E. Porsche had discontinued the regular 911 after 1974. Compared to a "regular" model, the S would have had a touch more HP. Maybe slightly different brake calipers (larger). There was also the 1975 Carrera, which was a 911S with spoilers and "SC" like rear fender flares.

While it is "restorable", the market does not really support restoring a '75S. As such, its value is low.. likely what Marconi mentions. Rust repair (by a shop) is never cheap