I must have lucked out. First DL agent I spoke with on the phone knew exactly what I was seeking when I asked for a mileage upgrade award. Flying TPAC and upgrade to Premium Select but not D1 was available. Confirmed with new seat assignment and RY booking class. Took 10 minutes at most. Mileage to be withdrawn when I board the flight, he said it was 25K miles but on a K fare, I gather it should (and may still be) 35K miles.