Well, I guess I can add some more information:
In 1985 Omega had the ref. ST 345.0809 and according to their Archives, only 1783 units were produced. They used the cal. 866 (not the current 1866) and had a hesalite crystal. There is this pic by Chuck Maddox :
This may be the (rare) model you are looking for.
Hope this helps.