The 1970s
Through the 1970s the R36s were the mainstay of the 7 service. The cars kept their original paint until 1977, when some were repainted in the new "Silver & Blue" scheme. Around 1975-78, the entire subway system was being covered in graffiti. Most cars had their original paint covered up by then or were given a new white "anti-graffiti" covering by 1982. By 1982 all cars had received air conditioning as part of a retrofitting program.
Read more about this topic: R36 World's Fair (New York City Subway Car)