Now I'm confused. My engine is 447 123 123: the cam is stamped w/ 447 so I am supposing the 447 in the '74-'77 of the list refers to the cam used but the model code I suppose is on the title ID on the frame, referring to the cycle itself, which I don't have. So judging by the # sequence I have a '75 XS 650 B engine--& I'm about to order OEM parts for a '76 XS which is on the BOS (probably not a problem so long as everything is based on the same cam--huh?)!!