HI Dave,
the more I thought about it, the more I abandoned the idea right now of OB with that driver. IT has almost no X, when you psuh it you can see that. So your intuition/experience is right. It is a beautiful 3 way 15" coaxial. It came in a large sealed box. Large meaning around 2-3 cubic feet. An old Altec sealed box.
The guy who sold it to me (some dude from tennessee) swore up & down it was one of the best drivers he had listend to.
I am going to listen to it there (believe it or not I haven;t heard them yet) and then decide. I haven't measured them yet at all.
It seems there are too many reasonable modern drivers around that are built for OB to muck around with vintage anymore.
-akhilesh