The truck in my signature is it. At about 70 mph or so I seem to get a howling or roaring noise in the truck. No vibration that I can feel or notice. Seems to be right under the cab or so. May be a little louder pulling a trailer or climbing a hill while accelerating. . Diff Fluids have been changed & lift is not much more if any in the rear. Going below 70 really not noticeable. Is this normal ? Wondering if an out of shimmed carrier bearing could do this. Any help that can be sent out would be GREATLY Appreciated.

 

Drive line at that speed would beat your ears because of high frequency. The center bearing alignment could be a issue if you raised the unit(unclear) some. Inspect shafts for damage and worn U-joints. Will it coast through in neutral???????

 

It has a leveling kit on the front, back had a different spring pack put on ,but didn't raise the rear much at all if any.
Stupid ? ,but what do you mean coast thru in neutral? Its really hard gfor me to desribe the noise, more of a roar [almost like a loud exhaust] than a howl. All the shafts & joints look & feel fine.

 

So like roll up the window...

Sounds like a worn driveshaft U joint to me. I had one go that sounded about like that. You'll have to take a close look at the drive shaft to determine which one. I actually had two go at the same time.