the abuntment bracket is shorter on the c5 setup, but the caliper itself is interchangeable. Brake overstock has the LS calipers and brackets powder coated red for $145pr and gm parts direct has the c5 abuntment brackets for like $35 each, My brackets were made by Purple reighn and made for the LS calipers.
The older CTS-V calipers that are 4 piston are interchangeable with the LS caliper but the " bracket" and caliper is all one piece but bolts in place of the LS calipers
series 1 3800sc (7.597 @88.53 1.579 60ft)
(series II swap in progress)
85GT Northstar/ 4t80e
86GT 3800 n/a