Today at AUS there was a Delta 767, although it may have been a 757, but I am almost positive it was a 767. The reason I hesitate to say with certainty is that due to the way it was parked my view of it from the spotters area was somewhat limited, I was looking at half of the body and a wing from the back. But driving off I got somewhat of a better look. Anyway, I was wondering if this is a new scheduled aircraft or a replacement. My first thought was that it was a replacement aircraft but while it was there, there was a Delta md-80, as well as 1 or 2 Delta 737s, which are more Delta aircraft than I have ever seen there at any one time. Also if it was a replacement it seems rather large considering the largest aircraft they usually send there is a 727, although in the off chance that it was a 757 mabye its not so much of a stretch. Any info or guesses would be appreciated.