Need Help. I have an '08 6.7 short bed. The truck has had a high frequency vibration since I bought it new. It starts at about 75 mph, and at 80 it buzzes enough to distort sight in the rear view mirror, and put your butt asleep. I've taken it to several different dealers and they can't find the problem. I just installed a new rear drive shaft with no improvement. I have 85K miles now and the warranty expires at 100K. If I can't resolve the problem before the warranty expires, I'll be forced to buy a ford.

 

I had a slight vibration at 62 to 67 mph. Balanced the driveshaft and the issue went away. Is your new driveshaft balanced? I assume your ujoints are ok?

 

If it's a 4wd, remove the front dirve shaft and take it for a drive. If the vibration is gone, you've found your problem. My front driveshaft vibrates at around the same speed.

 

I had to do my u-joints at 37K and ever since then, there's a vibration at highway speeds.

 

I've replaced the front drive shaft. After I bought the new drive shaft for the rear, I installed a harminic balance ring to the yoke and then had the assembly balanced. The vibration didn't change. I'm suspecting something in the rear end assembly.