the SN , LN, and date delivered are in reasonable order (at SouthWest) ? There are just the frames from AirTran - but their original delivery, LN, SN is still within norm.
C/n's 60082 thru 60086 have been announced recently, 36761 was the last delivered, they got 42526 months before that. I don't see any order here. In fact, Boeing abandoned their habit of numbering aircraft in one order sequential years ago, the first signs of this are around c/n 25500.