-NOV-20I3 MOS 51 737-SL-45-001 READINESS OF BOEING MODELS FOR Y2K. SERVICE LETTER RECOMMENDED 23-DEC-1998 MOS - (s) 51 737-SL-45-001 REV. A READINESS OF BOEING MODELS FOR Y2K. SERVICE LETTER RECOMMENDED 28-APR-1999 MOS - (s) 51 737-SL-45-001 REV. B READINESS OF BOEING MODELS FOR Y2K. SERVICE