Hi all, I have a 1916 HD twin cyl with the engine number xxxxM which is the correct engine case for the machine. My problem is that I also have an engine with the number xxxxxMD and I am not sure of its year. There are five digits and the inclusion of the letter D after the letter M which I can not find any information to explain.
I intend to restore the 16' with a side-car and commercial box and would like to know more about the other engine before I committee.
I would appreciate any help you can offer.