Ok so I went to a very resp muffler place & they found nothing wrong . I even went for a test drive with the guy & of course I could not reproduce the noise. But as soon as I got on the hyw the noise suddenly came back & has not gone away. I forgot to mention that I did a full brake job on the truck front & back. Rotors, pads clips were all replaced & slider pins cleaned & relubed. I checked everything recently with the brakes & they are fine. No unusual wear marks in the Rotors or anything.