I had this same sound on my '05 3.0 6spd manual, it drove me nuts when windows were down. I had some stuff done to the truck and the sound is gone, but I'm not sure what fixed it. They did front CVs, fixed a power steering leak, and changed all belts. Not sure if this will help but I had told my mechanic about it and when I picked it up the sound was gone and I forgot to ask what was causing it.