Rear rattle Aero V6 xwd

Hi all,

Sounds like panel rattle, had rear bumper off, checked/reformed heat shields, all interior rear interior trim panels,parcel shelf removed.........looked for anything obvious with all these off. Still there. Mrs sat in the back with interior panels off said it sounded like in the wheel arch.

Had inner wheel well cover off---nothing. Checked wiring all secure.......I'm out of ideas.

Suggestions anyone?

Thanks.