Hour and minute hands are wrong to this watch and come from another cal.861-powered watch.
Pushers have a very thin neck, interesting.
That bezel is correct and aged nicely.
45M is a serial for Circa 1986 so there is a good chance this watch is a whole bunch of put together parts.
The way to go would be to order an extract from the Omega Archives and see what comes back. This might cost you 130 CHF for nothing if your watch is what I assumed above as they will reject your request w/o refund in that case. Otherwise, if this movement is a Moonwatch movement, you will get an extract with the exact production date and it will probably confirm that the caseback is not original to this watch.
That's all I can say at this stage.
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