THe vibration does not get worse when braking. I can feel it throughout the entire truck. Steering wheel, pedals, seat, center console, my baby mirror that hangs from my backseat headrest always vibrating, my wife feels it in the passenger seat. Pretty much the entire truck. I have got the truck off the ground and drove it in the air. I still felt it but could not see anything unfortunately. Had a few people help me with that part.

 

A few years back I had a vibration in a 2004 Lariat that would get real bad around 40 mph. Rebalanced all tires, rotated them, changed the air pressure, etc and nothing made a difference. Was eventually able to isolate it to the front driver side wheel and discovered that some of the vents in the rotor were clogged with small stones and mud. Blowing it out with a pressure washer and using a punch and hammer to remove the really stubborn stones fixed the problem until I replaced the rotor.

 

Can you try throwing it in neutral from 38-45 mph when it's more noticeable? Just curious if the vibration is still there in neutral