I got lucky with this...first I bought some Polly Scale Glacier Green. But by the time I got it home....i decided it wasn't even close - to bright and gaudy. Then I posted here...I went with Fred's suggestion...I found Testors Pale Green. I thought it was pretty close, but it looked better in the bottle. I tested it on an undecorated hopper...but it was too dark and not 'minty' enough. So on a what-the-hell I, took a bottle of Polly Aged White I had on the shelf and transferred about 3/4 of a bottle to a larger bottle. Then I poured in some Glacier Green and mixed. I think it's perfect, an exact match. I'll find out when I paint an undecorated SD35 I am using for my green train. The bad new is....I didn't measure it out, I just eyeballed it....so I can't reproduce it to make another batch.
Photos to come....