Heard from a reliable source an undisclosed buyer has placed orders totaling ~60 airframes for the 738.

Any clues as to who?

I would hazard a guess that 50 55 of those will be Ryanair who firmed up financing on options last week.

LOL .. perhaps WN is eyeing on adding / replacing a new fleet for their planned acquisition ? WN is not a 'lover' of A320's and they "wouldn't be fleet-compatible" with WN's current philosophy and existing fleet ?

WN? No they are not a "lover" of A320s. Watch what happens if they get their hands on Frontier.

The 737-800 is too large for WN. They max out at the 737-700.

Often I try to book on WN and they are sold out. They have become the airline of choice for so many business travelers. So I wouldn't be surprised to see them reconsider the -800.

I wouldn't dismiss Ameican Air either. They have done a lot of fiscal house cleaning the past several months, including making room for and getting commitments for aircraft purchases.

The reason WN prefers the smaller 737 models is that they only need three FAs and they're quicker to turn.

You reckon 739's to replace some of their 752 fleet? The comments a few weeks ago by Arpey lead me to think it's something related to the RR engines AA has on their 752s that is the problem.

Wrong.

Southwest's business model isn't load factor driven, and their systemwide load factors are lower than almost all of the network carriers, so it's 99.9% that they won't be going for -800s anytime soon.