Feels like its coming from right under the drivers seat
The frequency of the vibration stays in sync with the speed, not rpm
but I dont really hear it until Im about 25 mph
Its really screamin on the expressway too

funny thing is...
when on the expressway, the vibration comes and goes as I hit a dip in the road and bounce around a little. As the weight of the vehicle lifts up, the noise goes away, when it bottoms out, the noise is worse
also, the noise goes away completely if Im going around a curve or if Im accelerating really hard. No change in the sound when I throw it in neutral doing 50mph.

My first thoughts are u-joints or wheel bearings. I checked for rubbing tires too cause it kinda sounds like it, but no burning rubber anywhere
I'm afraid it could be something tougher like the transfer case or the front differential, both had oil when I checked.

 

Sounds like universal joints to me. Check those first

 

Sounds like a front wheel bearing to me, especially since the noise goes away when going around a turn.
Part is $125 at Autozone.

 

A universal is the first thing that came to mind for me as well.

A wheel bearing typically will get worse in one direction, better in another. And even if it were a wheel bearing, do not cheap out on them. I have replaced 3 cheap assemblies for a friend and the last time I told him to spend the money for the good one. The first two failed in less than 2 months. The last one was 8 months ago and still going great.

 

I did the u-joints on the rear shaft first to no avail
they were the originals too, with 225,000 miles on them and still felt nice and tight

Next I did the wheel bearing on the passenger side 'cause it made sense to me the way the noise acts - no help
Im gonna do the driver side bearing tomorrow

another thing I found was when I took off the front drive shaft to do those u-joints. The u-joints felt good like the rears did, but the cv joint on the other end of the front shaft feels real sticky and rough. Im bettin that may be my problem. Hard to tell though without knowning what its supposed to feel like.

Anyway, that shaft to replace aint gonna be cheap is it?
OK well Im off to search
thanks for the help so far guys and I'll update tomorrow again

Kenny

 

Actually the CV shafts aren't all that much, just alot of labor on your part. I had a vibration problem that was caused by my CV shafts during suspension motion too. Is your suspension stock? Either way... with 225k miles, I bet the CV shafts are pretty well worn.

 

Actually, I hadnt got s far as the cv shafts up front yet
What Im talking about is the front driveshaft between the transfer case and the front differential
Its got two u-joints at the transfer case end, and a cv-type joint at the other end going into the front differential. This is the end that feels rough to me.

 

That definitely can be the cause. It should not be rough.

 

That may be a problem too but the cycling of the suspension would not aggravate it since the diff does not move with the suspension.

 

Check out this thread as well:
Vibrations - Hanr3