I do not have an answer for you as I have never tackled it, but I ended up having a leak in mine and the thing started whining real bad then grinding about 2 hours away from home. Ended up getting a NOS one from a buddy of mine in the UK. It had the proper gear ratio for the diesel but was for a E320 so I had to swap the input flange on it. Since it was brand new I just tightened the bolt back to the same spot it was and it turned out fine but I think you have to get it in the exact right spot using some sort of special measuring tool in order to do it the right way.