I left the city in 1966 with clean green cars-no air conditioning and the new kids on the block were the World's Fair Cars on the 7.
I returned for a vacation in 1978-- what a shock! grafitti all over--outside and inside. Smokers in the trains and no cops. They even ran short trains on the IRT mid-days. They ran mixed trains with multiple shades of red and some a/c cars on the IRT which was still green (under the grafitti). The new kids were the R44/46-cool a/c.
Another vaaction in 1983-- all redbirds, grafitti all gone, short trains gone, no green trains. No new kids this time.