Mark, an A at the end of a BN has been mentioned on a few forums and some people including myself thought the letter may have been done by an inspector at H-D for one reason or another. That sounded reasonable because we see letters and/or numbers stamped in various areas on engine cases and trans cases.
Then it was mentioned on CAI in December 2011 and below is a link to that thread:http://www.caimag.com/forum/showthread. ... ber-Suffix
In July 2012 on CAI the letter A was shown at the end of a 1941 45” BN. I remembered Bruce’s reply via the December discussion and because it had made sense I posted it.
Other BNs where I’ve seen an A include those for a 34VD, 1945 45”, 47 Knuckle, 49 Pan, 53 Pan and 61–62 Pans. At the end of the BNs of a 38UL I’ve seen a five-pointed star although I can’t say what that indicated.
But along with Bruce’s explanation I have to wonder if on occasion H-D just overstamped an incorrect character in the BN with the character that should have been used originally. For example, in my photo collection I have pictures of matching BNs 154-1++9 but the 9 in each BN appears to have been stamped over a 7. All the characters, including the ones I omitted, are the usual Harley types for a 54 Pan BN and there’s no sign that anything else unusual happened. I have a clear photo of the accompanying SN, all eight of its characters are the usual Harley styles for a 54 Pan, and there’s no indication that the number boss has been altered. Therefore in that particular instance I don’t think that the 9s were applied for any other reason than to correct a factory mistake.