One problem related to steering knuckle spindle has been reported for the 2006 Ford F-350. The most recently reported issues are listed below.
Truck started to gradually pull to the right when driving, after a couple of weeks took truck for alignment and was told that upper and lower ball joints on right side front knuckle needed replacing. Took car to Ford dealer and ball joints were replaced under warranty. Right front tire got worn on right edge and dealer said that the tire was not the responsibility of Ford eventhough the failure of the ball joints caused the tire to wear out unevenly.