I have a 2005 1500 2x4 with a 4.7L 36200 miles on it. I have a Vibration that shows up after 1500 rpm. I can make it do it in park. So I know it is not driveline. I do lots of Highway driving and at 70mph with the engine turing 1800 rpm I can feel it big time. Like I said I can do it in park all so.
So any help would be great.

 

i'd check all the motor mounts and the torsional dampener on the crank sound like it might be one of thoose

 

All the mount are good. I find that my fan cluch has some play in it. I can wiggle it all around.

 

If its anything like mine...03 4.7L same vibration....Your water pump will be going very soon. I had to replaced both the pump and the fan clutch.

 

That is what I was thinking.