I would think it is a CK 986 (T17 Inside) :
Here is a comparison with a CK 2111 (same case as 2104 but 23.4SC) :
CK 986 in a 1936 brochure :
Edit : By the way the CK2108 is not a Medicus, but a Naiad. Medicus stands for central second watches. There is a mistake in the Omega vintage database.
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