The rear track arm for the 997, part 99733104301 is the same as the front arm.for 986 and I think is why the 986 trw front arm.is no longer available. Meyle makes this arm.and on their site it cross references to 986 front, 996 front and rear, 997 rear. I ordered a pair from FCPEuro and they sent TRW. They were a perfect match and I'm running them on my car right now. I have another thread somewhere with more details.
http://www.meyle.com/en/service-centre/online-catalogue/?search=99733104301
This link should take you to the meyle part and you can see their part cross reference.