But it does provide some good fodder for the who's first question(s). So the 6105 dive case came out about the same time as the chronograph with a similar case http://thespringbar.com/the-seiko-6139-600x-collectors-guide/

: I have often wondered about this exact question -- What were the
: origins of the case style / geometry that Heuer used for the
: very first automatic Autavias (Reference 1163)? I wonder about
: some Seiko dive watches and some manual-wind Eternas? But these
: are just guesses -- both these could have come before or after
: March 1969.

: Perhaps there is no clear answer, but it would be great to try to
: unravel this mystery?

: Jeff

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