My 99 CTD with the 5 speed manual recently developed what seems to be a bad vibration in the driveline. It is much worse when the truck is under load ie. towing our 14K 5th wheel. Could it be the carrier bearing on the driveshaft or U-joints. Both I think are original. Truck has 221,000 miles. We are presently setting in a campground in the middle of nowhere Kansas. Any help would be greatly appreciated. Thanks, Dennis

 

If the problem just now started and having 221k miles I would be leaning toward those two items you mentioned.

 

Fixed the problem!!!! Took the truck to the dealer who was too busy, but possibly could see it Monday. Then took it to a private transmission shop. They were also busy but we went for a test drive. After a couple of blocks he stopped and unscrewed the shifter ball and the noise went away. Explained that inside the shifter ball, there was a jam nut that sometimes comes loose. After breaking the cap on the ball to access the nut, all was put back together and the jam nut tightened, my truck is as good as new. The best part, he would not let me pay him.