I've been thinking some about the difference between the "Fredo" we see in the movie, and "Freddie" as he's mostly called in the novel. Fortunately both versions contain the "Don't ever takes sides against the Family again," line, so with either interpretation of the character you can still go on to GF2. I'm wondering, though, who could play the tough-but-dull Freddie of the novel. I actually think Danny Aiello would be very good, except that he was in his late thirties at the time the first movie was made.

Maybe Pete, but Aiello was on the large size. The novel says Fredo was short and burly.

I figure that FFC wanted an actor who would physically portray the relatively weak character that Fredo turned out to be. To do so, he may have wanted an actor who was rather slight in build.

To portray the Fredo of the novel, I don't recall who of the actors of 1970 could have portrayed him. Maybe Michael J. Pollard.

I think Aiello would be too strong and assertive for Fredo/Freddie, and Pollard would be too goofy.

I'd reach into "Goodfellas" because Scorsese also was a master caster of Italian-Americans. My choices would be Johnny Williams (Johnny Roast Beef) or Tony Darrow (Sonny Buns), both of whom played occasionally clever but weak characters.

Now wait a minute TB. What about Tiny Tim or Pee Wee Herman in the role?