AFAIK they still sell those, albeit not OEM...I had one on my 1960s Connie replaced a year or so ago but can't remember for the life of me who did it...
Maybe try contacting Omega about it? There has to be someone making an after-market version (or selling at Ofrei, etc)
Best of luck and if I come across any info I'll PM it to you
EDIT TO ADD:
http://mb.nawcc.org/showthread.php?t=53182
and if you read this thread: http://forums.watchuseek.com/showthread.php?t=184904
whoever the OP is clearly knows where to get said xtals (just hit Control + F and search magnifier) - might try registering and PMing him. He also suggests Cas-Ker