Rolling noise

[69Bronc]

I am hunting down a noise in my truck. I recently purchased a 2000 F350. Ever since I bought it, I have heard a slight "rolling" noise. Kind of sounds like a metal barrel rolling down the road. It made the sound whether or not I had the hubs locked. It seemed to be coming from the driver's side.

So, I tore into the axle. The truck has 106,000 miles on it. I noticed that one of the wheel hub assemblies made a slight noise when I spun it by hand, so I thought that was the problem. I put two new wheel hub assemblies on the truck. Since I was in there, I also replaced ball joints (the uppers turned out to be fairly bad), axle u-joints, rotors (one rotor had a crack), and brake pads. I also repacked the hub-lockouts.

So, I threw everything together and took it for a spin - the sound is still there.
There is no vibration. I lifted the rear end of the truck up and spun the wheels the best I could and couldn't really hear anything. The carrier bearing has a little play, but usually carrier bearings have a vibration associated with them.

I am at a loss here. Any suggestions would be greatly appreciated.

Thanks,

Devin