What is “pre-code”?
Before 1934 movie makers could basically put whatever they wanted into a movie.The industry created its own code in 1934 to self-censor against certain things. For example, nudity. They were also not supposed to show a crime or a moral act and then the person getting away with it. Although there’s some haziness to that. The industry did it voluntarily it wasn’t imposed by lawmakers, although there were probably afraid of that happening. In 1969 they ended it and it was anything goes.
I believe this is called the “Hayes Code” but I don’t remember who Hayes was.
Sister Gloria played Grace Foster on an I Love Lucy episode.
Pre-code Hollywood was before the Hayes office came into being and there could be no more near nude scenes, graphic violence, etc.