Are pitman arms interchangable for different years? In Macs catalog they show 1909 through 1927.
I think the early 1909/10 pitman arms were shorter - see earlier threads:
http://www.mtfca.com/discus/messages/80257/98646.html?1247830227
http://www.mtfca.com/discus/messages/80257/88468.html