I now have my tractor back with a new drive shaft assembly installed from the dealership. My dealership has been good to work with, and even though the tractor is 5 years out of warranty at this point, they acknowledged the lack of information in the owner's manual concerning the driveshaft and u-joint lubrication. They worked with the regional JD representative, and we all agreed to pay 1/3 of the cost on the parts which was $663.66. JD paid 1/3, the dealership paid 1/3, and I paid 1/3. the dealer gave me a flat shop rate of 3 hours to remove and install the driveshaft - $ 256.00, even though they spent about 7 hours on it. They agreed to not charge for the pick up and delivery. I am about 30 miles away. Overall, I was out of pocket $500.94, and they had the tractor for about a week until everything was worked out. I felt it was a fair outcome. I took the old driveshaft to a driveline shop, and if they can find a replacement u-joint, it will be about $75.00 to repair the old one. So far they have not found an exact fit. JD does not have a part number just for the u-joint, and only sell it as an assembly. My guess is that is the way they get them from their supplier, and it was designed by someone other than JD. I cut an access hole in the plastic cowling, and screwed on a cover plate that I can now remove and keep the u-joint lubricated. hopefully I do not need to go through this again. Thanks everyone for all the information.