For past two weeks I am noticing a vibration. Similar to running across rumble strips. It is not road surface. It is not acceleration or braking dependent. Speed is not a factor. Drove a little over 200 miles yesterday. Interstate and back roads. Seems to occur when under "load" (such as small rise in roadway) and in 6th gear. If I lock out 6th I only noticed once or twice. 2015 Supercrew Platinum with 3.6 Ecoboost. Just over 125,000 miles. Thoughts? Differential, u joint?

 

my 2019 is currently in for rear diff repair. Seems the carrier and pinion bearings are experiencing failure. Parts on backorder.

 

Is it a high pitched rattle? Sounds like a ratchet or maybe like you're dragging a shovel?

 

mine was a roar at neutral load.

 

Just a big vibration. No "sound" to speak of...

 

check pinion angle