Seems there is a subculture of Uni-Mog enthusiasts out there in the U.S.
I've seen maybe one these things on the U.S. road in my lifetime.
Here are some sites to check out - http://www.scruz.net/~krs/ http://www.cs.brandeis.edu/~zippy/unimog.html
I'm also very interested in some 70s era Mercedes vans that were made, sort of like a larger version of the VW buses. MB bought a company that made buses using MB engine/transmission...Some are being maintained and operated in the U.S. I've lost my bookmarks on these things.