Joe's older brother and advisor, Stefano, led a mafia clan in Castellammare del Golfo.
I think you mean Joe Bonanno's uncle Stefano Bonanno.
What is the actual source identifying Galante as Bonanno's underboss?
A number of FBN informants. Carmine Galante became Joe Bonannos driver after 1943. By 1950 he was a Capo, by 1953 he was sent up to Montreal and brought members into the Bonanno crime family. 1956 he was acting underboss, 1957 he was official underboss. John Morale became official underboss in 1959.
FBI got informants from other families in the late 1950s in New York and New Jersey, interesting none from the Bonanno crime family (made members anyway).
