Ok - I haven't had the chance to work on post '96 rear brakes, but I looked up some info for you. It's a little vague, but it seems to go along with the W-body style rear brakes. The picture I have in the haynes manual shows two small box wrenches (the look like somewhere in the range of 10 - 12mm) one holding the sliding bolt and the other unbolting the caliper from the back. Just like the pre '96 brakes, there is no room for a socket, just a box wrench. I know your transverse rear spring is in the way of getting a socket back there. I think two boxes wrenches may be your problem solver.