Scott are you sure the cams are different?/ I think, again think, the difference is the distributer drive which is a separate piece on the nose of the cam that can be changed, at least according to what realoem shows in the E24 pre 82 cars. My car is an 81 euro built in May of 81 which was the first month and year of Motronic, and last year of the M90 so the realoem section shows views of different parts for the car. Again, think is the key word. There are also 2 different rotor drives for the front mounted dizzys and they are easily changed.