Dr No[Moderator Omega - Wristscan]
34913
That's a wide spread of manufacturers, h! . . .
Jul 15, 2022,17:41 PM
. . . if memory serves correct, GP dominated the last time trials in the mid-'60s. My hunch is that your steel GP is a production version of the movement that scored highly.
Your Zenith is also notable as most watches with El Primero movements do not have chronometer script on the dial, even though they are superb performers in their own right.
Thanks for sharing your collection; here's one of my sweep seconds Omega chronometers . . .
[Ω ref 2365 / cal 30T2SCrg]
. . . waving back!
Art