I have Spent over four years 'pinpointing' my noise, and I think it is mainly harmonic chatter in the prop-shaft (drive-shaft) CV joints.

It will not do it when up in the air on my 'wheels free' four poster ramp.

It recently became harsher, and more metallic and I thought the end was nigh, but it turned out to be the small heat shield on the down pipe that had carried away from it's mounting bolt, and it was resting on the drive flange of the rotating front CV joint. It all 'looked' OK untill I started poking round, and found it loose, so I secured it with worm drive clips as best I could....

If you 'dig' back through my postings (I think my very first), you will find a long report about that shaft, and it's joints, and how I improved it by lubricating them.

I still stand by what I wrote then.

Best regards.

Howard.

Isle of Skye.

PS. Having wrote this, I must say that your noises may not be the same as my noises. The wheel bearing noise was clearly cyclic in nature and not very nice. I have heard of them seizing up if left, so I confined it to local trips untill I did the job.