Hi Erich,
The watch is pressure shut and not screw in back. I don't know the reference as it was produced before Omega replaced the case serial number by the case ref (Caliber 30T2 n°9347XXX and case n° 10073XXX). I don't know the reference so it could be a 2192. Do you have a picture of it, there is none on the Omega VDB).
BTW I remember now that we already discussed the ref of this watch here :
http://omegaforums.net/threads/reference-2254-or-pretty-damn-close.8698/ Click to expand...