Hi there! I think this Omega resource is a decent one, but in my experience it has some holes:
https://www.omegawatches.com/planet-omega/heritage/vintage-details/14966/
This will bring you to a particular movement and case I'm researching, but just dig around in there a bit.
In this forum, there is a sticky thread that is called "all Omega calibers" which is also a helpful reference.
There had been an awesome, illustrated reference from Thailand called naligazone.com that has disappeared. I'm doing my best to find that owner and raise it from the dead, but let's see.
I've been referred to the Ranfft company site, but I don't find it very helpful. You might have better luck:
http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&2&2uswk&Omega_502
Again, it's on a page that interested me, but just dig around!
Happy hunting!
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