I believe someone here said before that Puzo covered the Bonanno family for a New York newspaper. This would make sense because the Bonannos, especially under Joe himself, and the Profacis were the two perennially Sicilian-centric families like the Corleones were.
If that’s the case, then maybe that’s where he got his knowledge from. I believe the term “Godfather†was used in the mafia before the movie came along but I cannot say for sure. Puzo said it was not if I recall correctly. He may have forgotten where he may have heard it.
