The calipers are from a clk55 (2005+).

The front rotors are from a C32 (since I wanted to go with 345mm instead of the super expensive 340mm SLK55 / CLK55 rotors. The rear rotors are from a SLK55 / CLK55 (330mm).

The rear rotors and calipers are a 100% bolt-on and go. Even the retainer screw that holds the rotor on lines up.

On the front rotors, the retainer screw didn't line up, so I had to use a lug bolt to keep the rotors in place until the caliper was installed. As for the caliper, I had to space it out 2.5mm (1 washer) to accommodate the extra 5mm in rotor diameter. I installed 1 washer per bolt between the removable mounting ear and the caliper itself.

Good luck.