WH / XH rear body vent replacements?

[multihull]

There is a rear body vent on the WH & XH found at the rear of the car hidden up under the left hand side of rear bumper. My vent is failing and letting in dust. Does anyone have a part number or know were you can buy a replacement vent? If I can't find one I'll just remove the old one and replace it with Race (Gaffa) Tape and seal up the hole.
The purpose of this one way valve type vent is to release air pressure from the interior of the car when the doors or hatches are closed, also when the fan is on blowing in fresh air.

[multihull]

Well this subject has got everyone stumped as there's been no replies. I've decided to make my own replacement vent as the OEM ones aren't up to it and will only fail again.

[ginga]

Hi multihull
I didn't reply because I couldn't contribute to what you asked.
I would, however, be interested in seeing pix & details of your fix as my WH lets dust in everywhere.