I have a 2000 F250 with 208K miles. She runs just awesome with no issues other than this weird noise. City driving no issue no noise. But on the highway as soon as I hit 65 MPH there is an awful loud super high pitch noise that seems to be coming from under the dash. Almost like an electronic sound. It's not the radio. I have owned and worked on 7.3 trucks my whole life and have never heard anything like this before. I have had two mechanics that specialize on 7.3 trucks check it out and they are both stumped also. Neither of them have ever heard a noise like this either. It is just so freakin weird. Letting of the pedal doesn't make it stop. But as soon as it drops below 65 MPH is goes away. Any ideas? Has anyone else had this issue? It's almost like it's possessed. It's really driving me crazy. PLEASE HELP!!