Actually, there are a lot more pictures of this guy. And it is not so dirty. I may just go for this look. (In fact, the only photo of 2001 on the web is mine.)
I did some light weathering on my Iron Belt SD38-2's - their orange is slightly redder, but the effect is pretty much the same. I made the diagonal black stripes on the side look "bleached" and applied a thin layer of soot along the upper vertical edges of the long hood. I can try to locate the photos if you're interested (I have them online somewhere).
[LATER EDIT:]
OK I found them, here they are:
...not exactly filthy but at least they don't have the shiny N-I-B look either!
I used a Testors Aztek airbrush to apply the weathering films. Diluted PollyScale Reefer White for the fading on the tiger stripes, Grimey Black for the [barely visible] soot along the upper edge, and a mixture of Roof Brown/Grimey Black on the end pilots. (The fuel tanks are a disaster, I'll need to redo them at some point.)
I think what you have is a good start on the fuel tanks for some of the peeling paint I've seen. Usually, there is deep red primer underneath the paint instead of rust, though.