Disposition MOC SL 737-SL-23-023 22-DEC-1998 RADIO COMMUNICATION COMPLIANT PINS. SERVICE LETTER MOS - Is) INFORMATIONAL 51 737-SL-23-024 COMMUNICATIONS-HF AUDIO DISTORTION ON OPPOSITE HF. SERVICE LETTER INFORMATIONAL 08-MAR-1999 MOS - (s) 51 737-SL-23-024 REV. A COMMUNICATIONS-HF AUDIO DISTORTION ON OP