Not that it would help when booking your flight, but I guess you could use these regos when you're glued to the window at the airport trying to figure out whether the aircraft you're about to board has the new j class or not:

A333 (330 with new F and new J)
B-HLP
B-HLQ
B-HLR
B-HLS

A34S (340 with new F but OLD J)
B-HXA
B-HXB
B-HXL

A34C (340 with New F and new J)
B-HXM
B-HXN
B-HXO