I have a 2011 F350 with 101,000 miles on it. Between 40 and 45 mph it starts to shake. Get over 45 and it quits. Get to 80 and it does it again. Stops after 85 or slowing down below 80. We balanced tires several times and finally bought new ones. It still did it so I bought new wheels because we figured maybe a bent wheel. Nope still does it. Been to a couple different shops and no one can find anything wrong. Any suggestions ?

 

Have the ball joints ever been replaced?
Where did the new wheels go on the front or rear or both?
Can you tell if there is more vibration in the seat or do you only feel it in the steering wheel , in other words is there a specific area where the vibration is worse ?
Is this vehicle with 4 wheel drive ?
Has any shop to the best of your knowledge checked the driveshaft positioning or attempted to relocate the indexing to see if the vibration could be made better or worse?
As you can see there are many possible causes for this condition and the more info you can provide might make it a little easier to offer a useful suggestion.

Has any work been recently done to the vehicle after which the problem became apparent?

 

New wheels and tires all around. Yes its 4 wheel drive. Drive line hasn't been touched nor the ball joints. The whole truck shakes.

 

I have difficulty believing with that mileage the ball joints are not worn.
Anyway, what some shops do is place the vehicle on a lift and get it up to 40 MPH and look for any possible driveline problems.
Have you considered a reliable Ford service dept?