I was going to throw out the possibility of taking a look at the "Susquehanna in Color" book as probably the definitive source. The book was authored by Paul 'Tup', so I'd say you won't get a much better answer (or source).
Yeah, I think if you compare it to the black of the undercarriage or the B&O hopper behind it, there's no question it's green.
I have made a passing attempt at finding photos of any of those other units and found nothing so far... but I did find this, which I found interesting. Unrelated, but still interesting. http://www.antiquephotostore.com/NYS&W.htm" onclick="window.open(this.href);return false;
