Four problems related to driveshaft have been reported for the 1999 Ford F-150. The most recently reported issues are listed below.
Transmission blew a back seal. There was metal and brass shavings in the trasnmission. The repair person said he believed the problem was being caused by "rear seal walking or spinning out, probably due to excess driveshaft moving or flexing. We rebuilt the transmission and a week later we are having the same problem. Except this time the rear seal got so hot it blew the transmission core also. I have spent 1700. 00 so far. No end in site and no help from Ford.
This vehicle has a a problem with driveshaft "run-up" it makes loud sound and you can feel it when stopping or acellerating. This vehicle has been in the dealship twice. The dealership could not duplicate until I took them for a test drive. The shop foreman heard and felt the driveshaft "run-up" he said they would repair it. I was contacted later and the service adviser said it was a normal sound. The vehicle was there for two weeks.
While traveling on the highway at 70 mph driveshaft broke in half. This could have led to a vehicle collision. Dealer notified, will not warranty the drive shaft because of modifications made to it.
Driveshaft was not balanced which caused vibration, the vibration caused the seal to fail resulting in loss of fluid and transmission failure.