Mr.V says on 23/Feb/11
Robards never looked as tall as 5'9.5 to me . I'd say he was about an inch shorter than that . In "Long Day's Journey Into Night" he was barely taller than 5'7 Dean Stockwell .

Here's a clip from the movie :

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And here's a clip of "Pat Garrett & Billy The Kid" where he's towered by 6'2 James Coburn :

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Watch the video from 1:06 to 4:10 .

In the final moments where the two go away together arm in arm it's clear that the height difference between them is quite big .