driveline vibration above 65mph?

[Dragond76]

Since this past winter I have noticed a vibration coming from somewhere in the driveline of my 2002 Tahoe. The source of this vibration eludes me still. Here is what I've done so far:
balanced front and rear drive shafts
balanced wheels
replaced trans mount
flushed rear diff
removed front drive shaft (issue persisted)
replaced u joints

At this point I am stumped, I know the truck is 14 years old but it only has 105,000 miles on it so I was hoping to keep it a few more years. If I can't figure this issue out I'm gonna have to replace it because I need a reliable tow vehicle.
Any assistance/insight would be greatly appreciated!

 

[cmc76]

id check your ball joints and wheel bearings

 

[Dragond76]

the ball joints are fairly wasted but I don't see how that would cause such a vibration? The wheel bearings are about 3 years old.

 

[ccapehartusarmyINF.(ret)]

at freeway speeds do you notice any slack when you breifly let off the gas a apply the gas

 

[Dragond76]

Tested that this morning, no difference. I'm thinking it may be the bearing in the transfer case.

 

[cmc76]

im voting to revisit the ball joints. you say they are "fairly wasted". if there is play in the ball joints, the slop can allow your alignment to be off in all kinds of conditions. At highway speed i dont see how you would be able to definitely say where the vibration is coming from.

 

[drakon543]

Bad ball joints are easily capable of causing a vibration. Your stuck on a driveline issue but this could actually be a steering, suspension issue or even just a wheel out of balance. Hell ive been in a vehicle that had a vibration at a certain speed caused by a cracked rotor.

 

[Dragond76]

I did have the wheels re-balanced last week and it did not help. I'm possibly trading it in tonight in which case I will no longer need to trace down the phantom vibration. If I don't then I'll swap out the ball joints and see if that makes any difference (I already have the ball joints waiting). Thank you for your input and suggestions, I appreciate it! =)