I happened to be driving past SFO on 101 southbound this afternoon and I saw an AS 739 with winglets parked in the remote parking area behind the A gates of the Int'l Terminal. I was stopped in traffic, so I got a better look than I might otherwise. Looks like ship 317, was originally intended to fly AS 220 sfo-pvr. No idea what happened, except that they subbed the inbound 738 from SEA that would normally turn and operate AS 307.