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The older style GM calipers needed Torx wrenches, which are simialr to Allen wrenches. For the C5 brakes, you need a 15mm open wrench, box wrench or socket for the 2 bolts that mount the calipers to the pins. The pins have to be held with a 16mm or 5/8" open wrench. The caliper mounting brackets require a 21mm socket, 1/2" drive on an 18" breaker bar. You only have to remove the caliper brackets if you are replacing rotors. If you cannot put the C5 on a lift, the front caliper bracket bolts can be loosened if the wheels are turned to move the brakes outwards. On jackstands, it is very difficult to get leverage on the rear caliper bracket bolts. You can lower the torque required by softeneing the Loctite by heating the mounting bosses on the bracket with a propane torch to 60 seconds. Good luck!