I'm posting this just in case anyone else has/will experience it.

My 2009 XF V8 (NA) would have a nasty sound coming from the rear end when accelerating.

It didn't make the noise all the time. Sometimes at 10mph, sometimes at 30 mph, sometime at 70mph but I had to be applying the gas pedal for it to initiate.

I was told it was the universal joint. I was told it was the prop shaft bearing. I was told it was the rear diff.

All plausible but I didn't fully agree because the sound wasn't rotational.

So recently I crawled under the car and noticed all of the heat shields lining the area where the drive shaft ran. Several of the heat shield panels were loose. So I put strips of foam between the loose panels.

The noise is now 100% gone.

I'm glad I didn't listen to the Jag dealer