So, we have a non-stepped (like the mk2) flat Oval-O with short indices on minute sub-register, left-aligned 'Professional' (that looks like an after-thought, but as I said earlier, just speculation) dial that apparently has feet for an 861 (and not a 321) movement whose SN is 31.318.xxx dated to second half of '71, and a DON bezel ... WITH an extract.
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