Another detail I noticed. It looks like it has applied markers, which, according to the pictures in the linked article, they didn’t do until the 16600.
https://www.hodinkee.com/articles/re...ex-sea-dweller
And the SD 116600 had markers all the way around the bezel, so it’s definitely not nearly as new as that. He also said the lume is dead, so that makes it at least 25 years old.
I think it’s got to be an early 16600, which would place it as late 80s/early 90s.