I have a vibration that starts at about 25 mph and continues to at least 80 mph. The vibration itself isn't too bad - buzzing in the floorboards, seats, etc - but it's accompanied by a very annoying low frequency growl. It is only present under load, when I lift off the accelerator the vibration/noise go away entirely.

I rotated the tires, I also changed out the rear diff fluid and saw nothing out of the ordinary there. This pretty much leaves u-joints unless someone has other thoughts. The rear u-joints were last changed 53K miles back.


'02 Excursion Limited 4WD
7.3L Powerstroke
292,000 miles

 

https://www.ford-trucks.com/forums/1...l#post12354798

 

Yes, I have that in a chart - it's what I'm working off and is pointing to u-joints or axle noise.

I'm hoping it's not axle noise, but it now seems more likely.

 

I pretty much had the same thing. Had my driveshaft re-balanced, and its driving as smooth as can be!