I have no idea what color is "OD" green. Is that Over Dose green as in what you look like when you over dose?
Anyway, my thoughts is that the green color is due to zinc chromate primer that is generally used on aluminum. I assume the green is also under the color coat on the top side as well. So, go get some green zinc chromate primer and see if the color is correct. I believe green and (mustard) yellow are the two most common colors of zinc chromate primer.
