Reviving an old post here because I found some new information that should help for future 591 owners (also, this is my first OmegaForums post!)
I found this post via Google during the research of my newly found 1960 Seamaster 14704. Mine also has a 591 with similar serial number placement. I was also a bit confused about why some 591’s showed serial numbers on the upper bridge and others showed the serial on the train bridge.
Well, I found the Omega technical guide had an interesting piece of info. Photo posted.
Quote:
“Movements the numbers of which range from 17420000 to 17439999 bear the sign (Omega), the number of the calibre (591) and that of the movement engraved on the upper bridge of the automatic assembly as shown in illustration opposite.”
So, it looks like OP and I both have 591’s from the fairly small set of 20,000 that, for some reason, Omega decided to do a bit different.
Hope this post helps the other 19,998 of you out there that think you may have a fake 591