I think there ir a relationship between the GF staff and the real Mafia, tell me what you think.

Marlon Brando(Vito Corleone)=?
James Caan(Sonny)= He was believed to have friends in the Colombo Family
John Cazale(Freddo)=?
Al Pacino(Michael)= He was arrested in 1962 I think for theft but I don`t remember
Robert Duvall(Tom Hagen)=?
Talia Shire(Connie)=?
Diane Keaton(Kay Adams)=?
Richard Castellano(Peter Clemenza)=?
Abe Vigoda(Sal Tessio)=?
Gianni Russo(Carlo Rizzi)= Some people say he used to work when he was a child for Frank Costello taking and delivering envelopes.
Sterling Hayden(Cap. Mc Cluskey)=?
Richard Conte(Emilio Barzini)=?
Al Lettieri(Virgil Sollozzo)=?
Al Martino(Johnny Fontane)=?
Victor Rendina(Phillip Tattaglia)=?
Morgana King(Carmela)=?
Lenny Montana(Luca Brassi)=?
Salvatore Corsitto(Amerigo Bonasera)=?
Richard Bright(AL Neri)=?
Alex Rocco(Moe Greene)=?
John Martino(Paulie Gatto)=?
Angelo Infanti(Fabrizzio)=?
Franco Citti(Calo)=?
Corrado Gaipa(Don Tommasino)=?
Tom Rosqui(Rocco Lampone)=?