One problem related to axle shaft has been reported for the 2006 Ford F-350. The most recently reported issues are listed below.
We have several 2006 f350 super duty 4x4 pickups. In the past two weeks two of them have broken out the eyes,on the left front axle, that retain the u joints. In the first instance , the spindle was then broken out around the upper ball joint eye. The steering control was gone completely at that point. In the second case the driver heard the axle break, stopped and turned the hubs out. The only damage was to the axle. The first incident cost approximately $1500 for the axle and spindle and the special tools to fix it. The second cost $500 for the axle.