Here is a link to the picture of the Atwood installed (Karl's site) :
http://www.westyventures.com/images/_MG_1814.jpg
Links :
http://www.americanrvcompany.com/Atwood-8012-II-12K-BTU-RV-Trailer-Furnace-8012-Hydro-Flame_p_32.html
http://www.dyersonline.com/Products/Atwood-Hydro-Flame-Everest-Star-12-000-BTUH__50467.aspx

Keep in mind, as Karl Mullendore points out, the  Atwood is rated at
12,000 BTUs, but is  75% efficient, so the real number is 9000 BTUs,
which is very adequate for our Colorado camping, though I am rarely
far from the house if it's less than 20 degrees.....that's just how I
roll!
Miguel