Beware of this fake "Military" case back being auctioned:

http://www.ebay.com/itm/Very-Rare-O...405?pt=LH_DefaultDomain_0&hash=item4d30887e5dPurchases made through these links may earn this site a commission from the eBay Partner Network

The markings are fake - the A/254/67 is the giveaway. FWIW this is the same marking on the fake provenance SM300 sold at Omegamania auction in 2007

 

The markings also look like they are done with a laser, and the fonts look too recent to be vintage....

 

Another fake, this time a complete watch, with the same fake markings:

http://www.ebay.com/itm/Vintage-Ome...920?pt=LH_DefaultDomain_0&hash=item33a0c75c30Purchases made through these links may earn this site a commission from the eBay Partner Network

 

LOL yes the 254/67 is the most common replicated fake caseback.

 

gone now...... kind regards. achim