Wristwatch collectors out there?

Anyone know when Omega changed the dial layout of the words in their seamaster lign? What I mean is I've seen models with the word "seamaster" directly under the Omega text, and some models have seamaster towards the bottow of the dial.. Seems like older Seamasters have it on the bottom of the dial and the newer releases have it towards the top. Maybe it depends on the actual model of seamaster??

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