N ELEVATOR FEEL PITOT PROBES AND RIGID METAL TUBING. SERVICE INFORMATIONAL LETTER MOS I8-DEC-1998 - (s) SL 737-SL-27-133 ELEVATOR TAB CONTROL ROD NUT REPLACEMENT. SERVICE LETTER INFORMATIONAL MOS I8-JAN-1999 - (s) SL 737-SL-27-134 REV. A TRAILING EDGE FLAP ALTERNATE DRIVE MOTOR DESIGN IMPROVEMENTS. SERV