With the discussion on what the A-321 pay rate should be relative to the 737-900 and/or 757...

If my memory's right prior to contract 2000 the 757 (200), 767-200, 767-300 and 767-300ER all had different hourly rates.

Before the 737-700 showed up it had a separate pay rate from the -800. IIRC it paid less than the MD-88.

I'll say it again: I'm really stoked Delta ordered aircraft, and especially that they ordered the A-321 over the 737-900.