It's a used ECM. It's the part number I needed. It functions. Everyone is a winner.
This is a used ECM. Presumably functioned when it was removed from a vehicle, and definitely functioned when placed in a second vehicle. Needed a specific ECM, this was the ECM, and it functions as it should. Just like the original ECM did. Until it didn't, and was replaced with this ECM. So, mission accomplished.