If I recall correctly forum member ZRX Mopar used to make brackets to adapt the 6 piston calipers for use with the 300 mm rotors but I also seem to recall a fit issue with the pads hanging off the rotor slightly which required a little grinding of pad material to not cause problems down the road. While I use 6 piston calipers on my ZRX front end know that these calipers are more problematic than 4 piston calipers. Need to be keep clean for proper action.