Duval played the part of Boo Radley in "To Kill a Mockingbird". This was in the early 60's IIRC.
I had forgot, or actually never knew, he was in True Grit. Looks like one of the older movies I am going to have to see once more, with pleasure.
I love to be reminded of roles "now" famous actors had bit parts in to start their careers.
This was pretty risque dialog for an 11 year old, but do you remember this scene?
[Rooster confronts the four outlaws across the field]
Ned Pepper: What's your intention? Do you think one on four is a dogfall?
Rooster Cogburn: I mean to kill you in one minute, Ned. Or see you hanged in Fort Smith at Judge Parker's convenience. Which'll it be?
Ned Pepper: I call that bold talk for a one-eyed fat man.
Rooster Cogburn: Fill your hands, you son of a bitch.