Here are two guesses, and only guesses. One, try tightening the front pinch bolt, I had the same rattle on my Milano, I tried tightening the front pinch bolt, it would work for a while, then it would rattle again, I finally broke the 10.9 bolt and had to replace it. How I finally fixed the rattle is I replaced the entire drive shaft with a spare I rebuilt. The front guibo was the same, but what I did find is that the rear bearing that goes inside the rear guibo was pushed in and not in the rear guibo, so I took my time and made sure the rear bearing actually made it in the rear guibo, since then this new driveshaft has not rattled. I am not sure this was the cause, but it was not right and it is a very easy mistake to make. I think you really need to mount the rear guibo on the drive shaft before bolting it up to the clutch.