Truck owner

I tried looking thru past threads. I thought somebody posted about a TSB for the 6.5 box's that had a drivetrain or axle vibration. My truck still seems to vibrate and you feel this in your drivers seat. My passenger seat shakes just driving on a smooth highway. Something doesn't seem to be right. Any thoughts or if anyone has this same issue?

Count Drunkula

https://www.f150forum.com/alldata.ph...011/makeid=20/