The deleted scene with Sonny's daughter, her beau, and Michael (one of the best, IMO) has a deleted scene of its own:

In "The Godfather Saga," shown often on US cable TV, at the very end of that deleted scene, Michael turns to a hulking young man wearing a plaid sport coat and says, "How's the football, Santino?" "Fine, Uncle Michael," he replies. That young man is Sonny's second son, seen for the first and only time. We saw his first son, Frank, in the scene when Vito comes home from the hospital, giving Vito a get-well. card. The "Saga" is GF and II, in chronological order and with all the deleted scenes spliced in where they belong, far and away the best version.