[tonythetarga]

you might send a PM (private message) to Bill Verburg. He generally moderates on the 911 Board. He is an excellent brake resource and may be able to nail it for you. If all else fails, I'd contact Brembo and find out what year and model they came from. Since the calipers are red, they either came on a carrera S, C4S or possibly a turbo. The stock 996 base C2 came with black calipers. Cayman S uses the same 996 brakes but I am not sure if they are stamped with the 996 part #. The 996S and 997's with red calipers are the same stamped number starting with 996.

BTW, they do look like they were used for track. One thing to be aware of from these types of calipers used hard for a long time...they may flex under braking when they get hot. That means that the pistons actually spread apart where the pad retainer is on top. The flex is hard to determine by watching but you'll feel it both manually when brake pressure is applied and when you put your foot on the brake for track use. You will find a soft pedal. If the calipers flex, there is not much you can do to fix them short of replacing the pad retainer with a threaded bolt that fits through the pads and tightens to prevent the flex.