2002 V6 4WD Low Speed Vibration

My truck is a 2002 4.0 L V-6 Off Road ext. cab that I bought new and now has 42K miles. There is a growling, oscilating, vibration coming from the right front wheel area that has occured at 40-45 mph for as long as I can remember. It goes away if I speed up above 45 mph or slow up below 40 mph. No other trace. I took it back to the dealer under warranty immediately suspecting a wheel bearing. I was told no, I had "chunk out of the right front tire", which they moved to the back and told me to leave it there. Same noise. I took it back again insisting on another mechanic. Young, ambitious Travis worked that truck over an entire day. They swapped in new rims/tires on front end, replaced the right front bearing, balanced my tires, and still the same old noise. They told me a used Ranger on their lot did this too and that was "...just the way they are". This is one dependable, sturdy, go-anywhere truck. BUT, that noise is darned annoying, and does sound dangerous. By the way, I live a small, midwestern town not unlike Mayberry. I play golf with the owner of the dealership which is 1 block from my office and 5 blocks from my house. I have coffee with (and the occasional beer) with any one of the mechanics and salesmen who I all know on a first name basis. I don't think they're going to try to screw me. I think they're out of ideas and can't find a solution and don't want to admit it. HELP!

Does the noise occur only if you are cruising at 45mph? What about revving engine while in park? What if you do 60mph and then let it coast down to 30 w/o any throttle? Does the pitch change with throttle or vehicle speed? What if you turn left/right when the noise is there?

Does the noise occur only if you are cruising at 45mph? What about revving engine while in park? What if you do 60mph and then let it coast down to 30 w/o any throttle? Does the pitch change with throttle or vehicle speed? What if you turn left/right when the noise is there?
The noise is not related to engine rpm. It begins about 30 mph when i speed up and quits about 45 mph. Likewise, it does the opposite when I slow down. Turning has no effect. As I speed up from 30 - 45 mph, the pitch does change, but only related to speed, not rpm.

The right side has an axle tube bearing that could be causing the problem. How is your front diff lube level and condition? Any off roading or impact to your front axle?

The right side has an axle tube bearing that could be causing the problem. How is your front diff lube level and condition? Any off roading or impact to your front axle?

Front diff. lube is OK and no off roading, or other, impaxct to the front ax. I'm going to bite the bullet, buy new tires, and align the front end to completey eliminate that possibility. The tires (Goodyear Wrangler RT/S P245/R7516) are now basically shot (at 43K miles) but were perfect when I started hearing the "sound" before 20K miles. Have to wait a couple weeks as dealers alignment apparatus is beign repaired.

just wondering if the tires are wearing funny and are saw toothing rub your hand over the tread usaully the inner tread and it should be smooth both direction but in a saw tooth situation the tire will feel like it is stepped or ridged the oppisite direction then what the tire spins and this will cause a growl hope this helps mike

are you driving on dry pavement with it in 4x4