78 SAC BASE ENGINES. SERVICE BULLETIN MOS POWER PLANT - GENERAL - INTERMIX ONE OR SUBSTITUTE ANY COMBINATION OF CFM56-76 SINGLE ANNULAR COMBUSTOR (SACO TECHNOLOGY INSERTION PROGRAM ENGINES OR CFM56-78 HIGH PRESSURE COMPRESSOR AND/OR HIGH PRESSURE TURBINE TECHNOLOGY INSERTION KIT ENGINES FOR THE TWO CFM56-78 SAC BASE EN