I may be showcasing my ignorance but I'd say you have a different problem than I had. My growl was speed dependent, had nothing to do with temperature (ambient or machinery), and never went away until after I installed a new u-joint and greased it up.

The fact that the intensity of the noise varies as you turn indicates a bad wheel bearing according to earlier posts in this thread.

Come and go shakes on the highway are most likely due to a wheel balance problem or possibly a bent wheel. I suppose a bad wheel bearing could do this too but I have no first hand experience with that.

I'll let you know what fixes this problem but due to the fact that you've changed your driveline quite a bit and mine's stock, my advice may not apply.

That makes sense because the guy I bought this truck from told me that he did his own brake jobs. He even gave me a extra set of brake pads. I will bet that he never re-packed the wheel bearings and at 146,000 miles they are wore out. I will have them checked out very soon. Don thanks for the help.

Hey Jake... Been on walkabout, spending all my spare time online doing research. Need the distraction of this again, need the simplicity, need a break. <img src="/forums/images/graemlins/cyclops.gif" alt="" />

Don... I'd really like to hear the outcome - keep me posted <img src="/forums/images/graemlins/kewl.gif" alt="" />

$$ - 3 to 6 K depending on condition etc.

Well, the noise is back although I think its a little different than it was before. I can also feel a decent amount of vibration. Both of these things vary linearly with speed (the faster I go, the louder it is). I replaced the driveshaft center support bearing last night but that hasn't really had any effect on the noise or vibration that I'm experiencing.

While I had things apart, I checked the rotation of the three u-joints that I haven't changed and they all seem to spin freely although I suppose they could have axial play that I really would not be able to detect by doing this.

My next steps are to:
1)Check the alignment of the newly installed bearing again
2)change the remaining three u-joints (they're cheap and easy)
3)Have driveshaft checked for runout and imbalance
4)start looking at other components like rear diff and transfer case.

In other good news, I'll be doing my rear brakes soon also.

I had something happen yesterday on the way home that got me to thinking about previous replies to my original post. I noticed when I went around a turn to the right at a good rate of speed that my noise seemed to go away. So I tried to duplicate that this morning on the way to work and I noticed that as I went through some curves at around 50 my noise would change slightly as I went around the curve to the left and drop off almost completely as I went around the curve to the right. Then I did a quick double lane change (left) and again the noise went away almost completely.

This points to rear wheel bearings being bad according to earlier posts here. However, the noise seems to go away no matter which way I turn if I turn hard enough. Two bad wheel bearings? Neither one felt hot when I got out of the truck either. Do rear wheel bearings still make sense as a possible cause?

The load/unload behavior is indicative of the inner carrier bearings (in the differential; the one that gets referred to as that on the driveshaft is the center bearing). Inspect the outer bearings first, naturally, since you have to pull the shafts to get into the 3rd member, but those should growl all the time if they're bad, regardless of direction.

I would suspect wheel bearings looooong before carrier bearings. Carrier bearing failure is fairly unusual whereas (rear) wheel bearings are expected to wear out eventually. I would suspect carrier bearing symptoms would change under different torque loads from the engine too.

x2... I'd probably go for wheel bearings 1st too.

Fwiw, I wouldn't be all that surprised that the noise would vary greatly depending on the loading. Turning hard would change the sheer forces being applied & thus you would have a variation on the surface mating. <img src="/forums/images/graemlins/cheers.gif" alt="" />