Which one on iTunes though, I found a lot of versions but I can't seem to find the one used in Raging Bull and The Godfather Part III.
The version used in the "Raging Bull" soundtrack is by Orchestra of Bologna Municop Thetra. Neither iTunes nor Amazon has that as a download. If you insist on having that particular recording, you'd have to buy the soundtrack CD. If you did, you'd get two more beautiful Mascagni opera pieces by the same orchestra: the "Barcarole" from
Silvano (heard during the color film sequences when Jake wins bouts, throws Vicki into pool, Joey gets married); and the "Intermezzo" from
Guglielmo Ratcliff(heard when Joey meets with Tommy Como. You'd also get tons more music (mostly '40's and '50's) that was and wasn't heard in the movie.
