I saw the message about my comment on a Model A engine in a 9N tractor and I knew I wasn't that old to be so wrong. I guess the 9N memory was wrong, but I know I drove the tractor for long enough with an old sickle bar to mow.
Here is a link that I got from a forum on old tractors that shows one.
http://www.ytmag.com/cgi-bin/viewit....oard&th=762775