Hmm, I have one bike that came equipped with 1st gen Dura Ace: Crane GS RD and DuraAce labeled FD (with cutouts on the outside of the cage) and downtube shifters marked "DuraAce" on the dustcaps. I'm not aware of Shimano barcons from that era, but who knows? Any model info printed on those shifters? A pic would help, too.

Neal