Mack AMI Diesel Engine ECM, ECU, Engine Computer Module, 12MS530M. Removed from a truck with a blown engine. Unit works as it should. Works as it should tested before removed.Most of our items are used and will show some sort of wear. We try to show any blemishes or defects that are out of the ordinary. If your in need of any other parts please ask we may have them or be able to locate them for you. We do this to try to help track the items and to insure they buyers receive their product. Thanks again have a great rest of your day.