The John Deere green goes back a LONG time before the New Generation tractors. The Waterloo Boy tractors were Green, with yellow wheels, and RED engines. Deere was already painting wagons green before then. The colors of tractors remained basically the same when the model "D" came out in the early 1920's. The red engines turned green at that point.
Sometime in the mid-1980's, Deere's traditional green changed ever-so-slightly, to a shade "brighter" green (with the same yellow) It was an attemt to make their product more visable. As the old green weathered, it got a touch darker. The "new green" weathers to a color near to the "original green" when it was new.
My theory is, someone at Deere knew how valuable their products were, even back in pre-depression days, and decided to make their tractors THE COLOR OF MONEY! /forums/images/graemlins/crazy.gif /forums/images/graemlins/grin.gif