Yes, it's the 7600 model. Except in 53, 54, and 55, they are pretty much unobtainable. It came in 1/8 and 3/32.
I do have a brand new 44 tooth 1/8" ring still in the package if you're interested -- black Dura Ace 7600, 144 BCD, 44 tooth, 1/2 x 1/8 chain. That's the smallest they ever made (and they don't make a 44 any longer in the current 7710 series rings). PM me if anyone's interested. I had to pay $86 for it ($95 less my team discount) but would sell it for the same. Not cheap, but very elegant. Much nicer than a Sugino 75.