Please make sure your front frame mounts (front of cab to frame) are okay and that your cab isn't sitting right down on the frame. These settle over time and if that happens you'll get a lot of noise telegraphed from the frame into the cab and as you would expect it is worse the faster you go. I used some PVC shower pan liner material (tough stuff) and built mine back up to where there was about 1mm space between the frame and the body. It did help.


~ Jon
1952 1/2 ton with 1959 235 | T5 with 3.07 rear end