Did some searches and cannot find anything similar, but my 08 CC F350 exhibits a vibration at 1750. If there is a slight grade it increases. It is the most noticeable around 65mph since the tranny has shifted out already, but you can feel it around 45mph (1750rpm) until the tranny shift to the next gear. I can feel it in the steering wheel, floor board and pedal. It is driving me nuts. I hate driving my truck like this, but am afraid the dealer is just going to say they cannot feel anything or it is normal. There is no way this is normal though. I did not notice it until around 1500 miles and then it seemed to gradually get worse.

 

I would suspect a loose or faulty U-joint or wheel bearing if it gets worse at higher RPM's and has been getting worse with time. Of course an unbalanced wheel or bad tire can cause a similar vibration too. I would definately say it's something in the drive line if you can feel it in the steering wheel and floorboard. But maybe someone else has a better idea?

 

A U-joint was my 1st thought.

 

If you feel it mostly in the steering wheel then I would guess a front tire, alignment, or wheel bearing. If it is mostly seat of the pants and just barely in the steering wheel then I would agree its in the driveline somewhere.
If it only does it when towing then you have a driveline angle issue. This has been common on many trucks as the load changes the angle and stresses the U-joint. Ford can just shim it. The driveline angle could also be a cause if you have added a lift kit or bigger tires.

 

I've had that happen before and couldn't find the cause for quite a while, turned out the driveshaft was out of balance, they just weighted it like you would an out of balance wheel, just somthing else to look at.