Thanks to all who have answered my questions so far. I hope to gather enough knowledge to return the favor!

I've recently developed a vibration at 45-55 MPH. It seems to go away if I use tow/haul. It sounds like 'rawr--rawr--rawr--rawr' (go ahead, you can say it out loud ) about one 'rawr' every second. Tire? U-Joint? Wheel bearing? or is something about to asplode? I can't seem to figure out why only in overdrive.

Ideas?? Thanks in advance!

 

check the carrier bearing to if you have a long bed.

 

i had this too, for me it was belt seperation under the tire treadbut probally not what you have cause of the gone in tow haul thing.

 

I should add that it is present when I let off the accelerator, too. Not just under load.

 

Okay, I'm not trying to beat this one into the ground, but one more try before it goes to the dealer... Thanks for the suggestions so far, but still haven't been able to nail it down.

The growl went away on its own for about a month. Recently we had some snowfall and I engaged 4HI. When I took it back to 2WD the growl came back! That's how all this started to begin with. Is there something that can stick that would cause a growl between 50 and 60? Knowing my luck it will stop growling as soon as it hits the dealer lot.

 

Have you checked your ujoints and carrier bearing?

 

No carrier.. it's a short bed but the U-Joints are looking good. Does the front drive shaft turn in 2WD?

 

Once in a while on mine, the electronic shift transfer light would report switched back into 4H but it wasn't. Whenever that would happen I would back off throttle, shift into Neu and then back into Drive. Got into the habit of doing that whenever using 4W4.
Have you serviced the transfer case??

 

No, I haven't and I'm at 36,000 miles. I'll do it this weekend.

 

That sounds exactly like the symptons on mine. Ujoints looked good and were not warm. After a while I decided to pull the shaft. I removed the 4 bolts holding the flange to the rear end and knew I had found it. The rear joint was very stiff and when I started knocking it out, rust and broken needles went everywhere. Don't just look at it, pull that shaft.

 

Good plan. I think I'll put new joints in the rear shaft ASAP. Now the next question...

Spicer or Precision?

 

Good stuff, guys--I am having a similar problem. Mine is at 70-75 on the highway. Comes and goes, and happens both on the straight and in curves. My mechanic looked at it last week and found nothing positive. Checked all the U-joints--none hot and none showing a rust ring. Doesn't think it is the tires. I am sure time will tell...

 

My truck has developed this same noise over the past few weeks...guess I'll check all the above recomendations and proceed from there