Leaving Rick alone with pastels is almost as bad as giving him paint!
Last year when I posted an RDC picture on the PRSL Historical Society site I got told that the RDCs were delivered with a dark blue undercarriage, not black (as if I could tell the difference). So today I pulled out the weathering powders and attempted to put a blur tinge to the black undercarriage. I cannot tell the difference in person but the camera picks up the blue (too light of a blue).
While I was at it I also added a grimy black to the fluting and darkened the fans on the ConCor units.