So I have been trying to figure out if the heads are specific to the driver or passenger side or if they are interchangeable. With there being no differentiation in the part number to call out driver or passenger side I would believe them to be interchangeable. From looking at many pictures it seems that the only difference is how you set the cam in the head and which coolant/oil holes are open and which ones have plugs. If there is a difference in the driver and passenger head, what are the differences?