I haven't had to replace that part so I can't speak to what is required, but if I was going to buy it, I'd buy it here:
Porsche Parts at Dealer Cost
http://****************************************************.com/renntech.php
Phone: 1-800-346-0182
Email:
porscheatcost@****************************************************.com
I have found they have very reasonable prices and are very helpful over the phone.
Dave S.