04 F250SD FX4 5.4 Whistles when first driven
 

The whistle or squeal begins when I first start rolling. It progressively gets louder the faster I go and quieter if I slow down. Then after about 1/4 mile it stops. Thought it was trailer brakes because the trailer sat all winter. Drove a 50 mile trip pulling an empty car hauler on interstate, loaded a 9N Ford tractor on car hauler and came back. No whistle/squeal sound. Unloaded and unhooked and later drove to town. It did it again just like before but without the trailer hooked up. I turned around and put it back in the barn. Haven't had a chance to look at it today. Truck has 65000mi. Has anyone seen this before?:cool:

Sounds like you have a u-joint on it's way out. If they are original, no way to lube.
Look for rust trails at each joint . One of them is running dry ! Get it before it gets really bad.