Hi,
I have 262 of 268 that I think are known. That Duren is one of the six I need. Here's the other 2 Duren's. I have a picture of the one that you are asking about but can't find it right now. I don't think there's much else to know about it except that it's one of the highly scarce variations from this set. I don't have a reference guide that lists it either.
-Andy
