I may have just answered part of my own question.
from real oem, seems is a GS6-37DZ where as the 330d and even the 123d have a GS6-53DZ.
Next question is what do the numbers mean? I read on another forum that the "37" relates to the max torque so 370Nm for the 320d and 530Nm for the 123d and 330d
Can anyone confirm/correct me on this?