Just my opinion, the dash color is not a medium copper or a dark copper. I think it is a brown with a hint of copper.I thought 66 had the smaller dia. column. 67 was larger because it's collapsible.
Good point about the GTX as I have no idea what's been done to that car and what is/isn't correct. Don't care for the color combo either. However, the Dark Copper, if close to correct, looks darker than my original dash color which is darker than the Medium Copper so I still think my hypothesis in post 16 is wrong.