I installed new front shocks & a new transmission mount & the vibration is still there.

 

Did you watch the tread? I had a tire on my Impala that balanced perfect. It had a slipped belt and the tread would visibly wiggle when rotating. The tread moving sideways gave me fits until I noticed that.

 

Yes I checked the tread & replaced the front tires because I saw some dry rot, & had all 4 balanced
I even switched the tires & wheels from my 94 Dakota & it made no difference with the vibration.
It's starting to drive me nuts, I've had 2 other mechanics look at it & their as stumped as me.

 

Have you had the driveshaft checked for balance?

When the sway bearing was replaced, did they double check that they keyed the two halves properly?

RwP

 

If you can find a highway with three lanes, have someone else drive your truck at the speed that makes it vibrate. You follow in another vehicle and watch the suspension and wheels when it starts. Three lanes means you can move back and forth. Eventually, you'll see something not moving like it should.

 

I replaced the center support bearing myself & to check the balance with the differential on jack stands I attached a piece of metal to the bottom of the differential with a magnet that I could put a glass of water on & watch the movement of the water while running it up to 100 mph.
The water was bubbling on the surface but not splashing up & down indicating that it's not out of balance.

 

Good idea, I'm planning on doing that tomorrow or maybe today if I get some time.