Originally Posted by
sbagdon
This doesn't appear to be a question of base-fare (H/M -> A/DL?), this appears to be a question of fare flown (A for DL, H/M for NW?).
Exactly. On DL, regardless of what the 'original' fare basis was, the flights post as just "A", and earn miles accordingly.
For instance, if you purchase an MA00UPNA fare, the flight just posts as "A" on DL,
not "MA". Obviously, NW is posting them based on the 'original' fare basis. All of the "A" fares I've seen lately are MA00UP or YA00UP, which should qualify for a fare-based bonus, but Q and H used to be common 'original' booking classes for DL A fares. If the OP still has their itin that DL.com emailed, the fare basis can be read from that.
Interesting that NW is saying they can't tell if it was H or M, especially since M would qualify for 150% EQM.