60 MPH droning noise after lift...only when throttle is open

Mine is a regular cab. The noise was there before I got the recall springs. I think it's the drive shaft slip yoke or u-joints. I'm going to get new u-joints first. I'll have the lift on it mid January so I'll look into the shims then.

 

How much of a lift did you have using the 3 degree shim? I have only a 1.5 inch rear lift and immediately got vibrations. What size shim should I use? I'm thinking a 2 degree shim. The 2 incher is the closet available.

 

It was a 2" AAL added to a brand new recall leaf pack. So I ended up getting closer to 3" I think.

 

2 degree shims cured my driveline vibration. Smooooooth.

 

I'm experiencing exactly the same symptoms you described, jbrewster, after installing new Bilstein shocks all around, new heavy duty leaf springs, and a set of Firestone Ride-Rite airbags that require a minimum of 5 PSI at all times. This suspension mod lifted my front end 1" and my rear end 4.5". I did this to permit towing a 3000 lb travel trailer while maintaining level (which requires 10 PSI airbags). The only difference in my symptoms is that the noise starts at about 25 mph, is loudest between 30-45 mph, and is harder to hear at 50+ due to higher frequency, road/wind noise. Question: Did the shims you added eliminate your vibe/sound when your truck is both loaded AND unloaded? Because it seems to me that the same shims that help your unloaded geometry would hurt your loaded geometry.