I will second the others, OD can be/weather to lots of different shades, so pick what you want.
I love the AK Interactive Real Colors line, they have at least two US OD's ("regular" and "faded") as well as a few others I think. They airbrush very very well in my experience. Get some of their thinner to if you try them...they say they can be thinned with lots of different things, but I like to use their brand. Goes a long way (still on my first bottle) and works great.