My good friend with a 1998 12 valve smelled burning oil a couple of days ago. Stopped and opened the hood and oil was coming through the gearcase right where the KDP is located. His truck has 170K on it. It was the KDP and he took it in to Cummins for a new front gearcase etc. Two years ago when I tabbed my KDP he laughed and said I worried too much and that failure was so rare he wasn't going to worry about it. He called me after his problem and said it looked like I did the right thing after all.