Two problems related to axle shaft have been reported for the 1999 Ford F-350. The most recently reported issues are listed below.
Transfer case shifting fork wore out. Truck had only been in four wheel drive about a dozen times all in snow conditions on major hiways. No offroading at all. Had to replace the shifting fork, a planetary gear an a imput shaft. This was the only way Ford would sell the repacement parts. Ford has made a design change on the shifting fork.
Pilot bearing went out completely, pilot shaft went into pilot bearing. Consumer was not able to shift gears, it was not driveable. Consumer replaced pilot bearing. Currently, it went out again. Took to dealer, and they replaced pilot bearing and pilot shaft.