- INCREASING OF BOLT LENGTH ON T49.5 PROBE BOX. SERVICE BULLETIN COMPUED WITH -AT MANUFACTURE MOS 16-DEC-1998 HRSAISC - 0 ENC 0 SB 72-0160 NO.2 ENGINE - REMOVAL OF INTERNAL INSTRUMENTED HARDWARE ON COMPLIANCE ENGINES: 874-101 THRU 874-105. SERVICE BULLETIN MOS HRS/MSC - ENC SB 72-0161 NO.2 ENGINE - REPLACEMENT OF E