I have touch up paint for my Cinnabark exterior paint job that includes a dark charcoal grey, called Charcoal Mesquite Grey. It is one of the paint codes listed on the ACA technical forum for the paint codes for the '06. If you're anywhere near Palm Springs I could let you try mine and see how it matches, otherwise, if you wish I can help direct you to that paint code and the supplier from the paint code on the technical site. Send me a PM and I'll help you with it if you wish.
Former Owner, 2006 36MDDS
2010 Arctic Fox 22GK Travel Trailer
2007 Toyota Tundra