how can you tell if your engine is internally or externally balanced on 2000 Ford Mustang

going to change the clutch and want to change the flywheel while im at it but there are 2 kinds of flywheels internal and external

1 answer
See last post! You must have the 3.8L V/6 engine....What is wrong with YOUR flywheel?? There is only 'one' part number..!!!