The Germans are the best when it comes to getting parts for old cars. I used to get parts for my Ponton with no problem from RBM in Atlanta. They had to bring them in from NJ but they had almost any part I ever ordered. In Germany. Mercedes has there own used parts depot outside of Stuttgart.
http://www.mbgtc.de/index.asp I doubt that Ford has that. However, I know that parts are available for many of the more sought after American cars over the last 40 or so years, such as the Mustang and T-Bird. But all that stuff is not from the dealer. Maybe try Hemmings Motor News.