I had a slight vibration in my coach for a while. I drove it down to new jersey last week and once I got home, it was not the same car I drove down. Went to napa and picked up a new U-joint. The old one on the slip yoke on the rear shaft had completely came apart. The was no grease in it just rust and chewed up metal. Long story short, make sure you grease these things if you can.