Those were the days of reverse ageism......
Stewart's darker range is often visible in his Westerns for Anthony Mann....and to some extent VERTIGO. Though neither he nor Wayne are chameleons by any stretch.
For my alternate Oscars, John Wayne is unique by getting Best Actor four times. Not for TRUE GRIT.......but for RED RIVER, THE SEARCHERS, RIO BRAVO, and, for pure sentimentalist reasons, THE SHOOTIST. (I won't pretend he gave a better performance than Dustin Hoffman in MARATHON MAN, but I'm mirroring the eccentricities of the real Oscars here.)
My only Best Actor for DeNiro lies with the spectacular CAPE FEAR remake.