Mustang 8.8 rear disc

I believe some of the Mustang rear calipers (94-04) have an integrated parking brake that require the piston to be rotated to move the piston back in the bore. There is a Helix inside that when the parking brake lever is pulled pushes the caliper out to set the parking brake. This needs threaded back in to compress the piston. There is a tool for doing it, some use needle nose pliers. There is a pair of spanner wrench type notches in the piston that you can engage. Ford/Mustang is not the only MFG to use this method. I've seen it on Lincoln, Audi, and Mazda and probably more. My dad pressed the pistons in with a c-clamp on the rear of his 94 MK VIII and trashed both calipers.