BY a 737-SL-09-002 REV. A). SERVICE LETTER MOS REPORTING FUEL IMBALANCE EXCEEDANCES TO BOEING. SERVICE LETTER MOS MOS St 737-SL-09-002 REV. A TOWBARLESS TOWING (SUPERSEDED BY a 737-SL-09-002 REV. B). SERVICE LETTER MOS St 737-SL-09-002 REV. B TOWBARLESS TOWING (SUPERSEDED BY a 737-SL-09-002 REV. C), SERV