can you hear the sound by revving the motor to the rpm of 60 mph?

A couple of questions. Are all the windows up when this happens? Can you change the noise using windows or vents? The reason I ask is my Camry thuds my eardrums above 60 mph with the left rear window down. Yeah, left only.?? This may be the same noise as the Audi prev. mentioned. My answer is as simple as rolling up a window. Is it possible you have air leakage into or out of the cabin that could be causing it?

My truck started doing that, about six months after I had the engine rebuilt. Had the driveshaft balanced, finally fixed it by torqueing the bellhousing bolts.

HR369 - the symptoms are related to vehicle speed, not engine speed. I can rev to redline in lower gears with no noise/resonance.

Mark - I'll have to do more testing about this, but it certainly happens when the windows are up.

Stanley - I suspected the driveshaft, so I replaced it with a new, balanced, one.

Thanks for all your suggestions.

Does the noise have a cadence to it - as would something that rotates?

Sounding like a bad diff due to either the bearings, or uneven gear lash around the ring at this point. If it is wind noise, it should change by opening/closing windows.

I agree with improper lash on the ring and pinion.

I've had to redo my land cruiser for the exact same reason.

To describe it as best I can: It's a powerful reverberation bass noise that comes on suddenly and doesn't go away.

Is there any way to check the diff without replacing it?

gear backlash can only be checked with the diff opened up.

Mixelplix,

Your description sounds like what I'm experiencing. My symptoms start at 60 mph and increase with vehicle speed and I've been afraid to drive it over 70. If the gear backlash is adjusted is it likely that there will be gear whine or other noise caused by the worn ring and pinion?

Here are a couple things to check

How far away is the exhaust tubing to the diff housing - is it touching? Is you exhaust hung with rubber strips or are they hard hung? Have you driven the car at 70 MPH and pushed in the clutch and listened? Have you rotated your half shafts 45 degrees to see if that helps - you could have a u joint in a bind on one of you half shafts. Remove both sides and inspect the U Joints on both sides - you can not do this with them on the car. Make sure they are moving freely in all directions

I'll check the exhaust. All six u-joints, including the driveshaft, have been changed. Didn't help!