Here's the link to the outfit in NJ we've used for S4 rebuild kits (Brembo 4 pot design). Not sure they'll have anything for the sliding caliper, which I think is made by ATE.
860 291 9415
Here's a link you might find interesting. Its in German, but pictures say a lot.
I will get back to you.
1992 Porsche 928gts midnight blue