T CAR ECM COMPONENT CROSS REFERENCE CHART CONT D PRODUCTION SERVICE SERVICE PRODUCTION PRODUCTION BROADCAST CONTROLLER CALIBRATOR CALIBRATOR ECM CODE ECM PROM PROM CODE 1987 16030121 BOU 1226020 1226663 7576BOU 16030131 BOW 1226020 1226664 7581BOW 16030151 BOY 1226020 1226665 7591BOY NOTE when replacing the Production ECM Controller with a Remanufactured ECM Control er it is important to transfer the Production Broadcast Code and Production ECM number to the Remanufactured ECM Controller Label Please do not record on ECM Cover This will enable positive identification of ECM Components throughout the service life of the vehicle 1 1991 GENERAL MOTORS SERVICE PARTS OPERAT ONS CHEVROLET 17W 3 999 3 228 6 91