Good Afternoon Ladies and Gentlemen, I have a friend who is selling his nice omega vintage watches collection. Among his timepieces there is a SeaMaster ref. 166.028 in fantastic conditions (it still have an original shark leather strap), the only thing that I’m really not sure about it is the movement: this watch cases a cal. 565, but what I know is that it should have a cal 563 for the non chronometer version or the cal 564 for the chronometer version... I’m missing something or that cal 565 is not the correct movement for that SeaMaster? He is swearing that he bought the watch from an old AD 20 years ago and he didn’t touch it since then. Thank you very much to everyone who is going to help me to resolve this mystery.