This came with a job lot of painted 15mm ACW figures. It was a bit worse for wear so I set myself a goal to restore it. The canvas was taken apart and reset and the overall paint work tarted up. A driver was added and the whole lot rebased ready to add some novelty to my next Fire and Fury game.
Thanks to the Internet I was able to work out that this wagon was an ambulance called a "rucker". Here is a link to more information than you could ever hope for about ACW ambulances: http://www.civilwarhome.com/ambulancewagons.htm.
It was the "most serviceable ambulance wagon used during the latter part of the war ... designed by Brigadier General D. H. Rucker, and built at the Government repair shops at Washington."
I don't know the manufacturer of this model (yet).
It is possible that the canvas should be glossy black representing oil cloth or rubberised canvas. The wood could possibly be a bit more green. All I know is that it is now a serviceable model for the miniature battlefield rescued from the bits box (as distinct to coming off the lead mountain).