It's hard to know. Here is what I got from Vacheron Constantin:
Dear Dr. Sanders,
Thank you for the message. In regards to your inquiry, the movement caliber for the Overseas 42040/423A-8, serial number 677714 is Caliber 1310; which is an automatic movement with 27 jewels. Please feel free to contact me if I can be of any further assistance. As always, I remain at your service. Best regards, Melanie Vacheron ConstantinNorth America Concierge Service ----------My Response---------- Cher Madame Concierge Melanie,
Thank you (and the archive department) for all of your help with my Vacheron Constantin Overseas' identity.Were I to purchase another Overseas 42040, I would like to know what year that Vacheron Constantin changed ébauches from the caliber 1310 to caliber 1311. (My 1996 houses a cal. 1310.) I realize that this is a difficult query and the Archive Department may not have that information. The reason I ask is that I understand that the caliber was changed to make it a bit more sturdy for the “sport” type of watch that is the Overseas design.I realize that they may not be able to answer this question, but that’s Ok if they do not have that information. They (and you!) have been a wonderful help already.Bien sincèrement,Dr. W. Sanders
Dear Dr. Sanders,
I hope you are doing well.Our Technical Department responded today regarding your question concerning the caliber 1311. They have confirmed Vacheron Constantin started using the 1311 caliber in the Overseas 42040 when it was launched in 1996.We remain at your disposal should you need any further information.Best regards,MelanieVacheron ConstantinNorth America Concierge Service--------
So it's hard to say. Eric Edelman may have got the "wrong" information from VC--clearly it depends on which response from VC one chooses to believe. For me, it's a delicious mystery! For now, though, I'm going with the 1311 "history."