I still recommend the SWEPCO 712 20wt. ATF and so do Porsche 928 users who have the same automatic tranny.
:-) neil
Try below (call them- not listed on their website); your local Porsche independent; or your local Porsche club.
http://www.drivewerks.com/catalog/shopcart/CARE/POR_CARE_SWEPCO-detail.htm
http://www.rwparts.com/catalog/index.php?cPath=62
http://www.pap-parts.com/store/products.asp?dept=2538