Vibration no one can find

If a engine balancer goes bad can the vibration be felt at high idle?
Same rpm as going down the highway...

 

Not necessarily...But if it's the harmonic balancer all you would have to do to check it is take the truck out of gear while going down the road and let the RPM drop. If the vibration stops that could be the problem, If not...

Mine was vibrating like that when I first got it and it turned out to be the caster/camber was way out...But that wouldn't show up on a dyno.

 

If it the Caster/Camber being out, It will be wearing steer tires out early....70,000 to 80,000 miles. If it's really bad it'll wear them out in 40,000 miles or so, You'll also notice them cupping out within 25,000 miles or so.
Steer tires ought to last at least 130,000 miles or better if everything is set up right.

At any rate...it doesn't sound like it's engine related if you have already done the coasting thing and it makes no difference.
Has it always done this or did it recently start doing it?
If it just recently started doing this...Did it come on slow and gradually get worse or start all at once?

Since we have all but eliminated internal engine problems by coasting it then it is narrowed down to either gear train, Drivelines or wheels and tires and related components such as brake drums that can and will cause vibrations under some circumstances.

Also...Is it speed related? Slower speed, Slower rate of vibration?

 

so hows it comeing with the shakes?did youcheck the shafts=angle=balance=trueness=spline alinement.any of those are of and itll shake up like a monkey.

 

Does the rate of vibration change at all as the speed changes?
Is there any noise related to the vibration?

 

Well...I'm stumped!

I'll think about it...But I've never heard of anything like that.