Interesting. Thanks for this reply. It seems like D1 marketed aircraft from JFK are pretty religiously LAX, SAN, and SFO. I’m sure I’m missing a couple TCON routes but doubt those routes (maybe partially LAS when they don’t put you on a 737) would ever be FC aircraft on their B752 or 763/764 aircrafts. Good to know.
So I updated my post after you posted. This is a D1 fare rules issue as DL hasn't updated them yet to include A330-900neo aircraft on domestic D1 routes, so they currently default into booking into FC fares. They did, however, manage to already add it to the FC surcharge equipment list in the FC fare rules (so, unfortunately, you'll be stuck with that). I'd fully expect them to update the D1 fare rules to include them in the not too distant future. Maybe they'll take out the 777s while they're at it (since they are gone now).