I've just taken delivery of a complete LS1 rear axle as I intend on doing the LT1 to LS1 rear brake swap, I was only counting on the mounting hardware assuming I'd have to get new rotors and pads but I was quite chuffed to find all the pads and rotors were almost brand new.
I don't know the donor cars history but it was a 2001 LS1 A4 and is currently in a salvage yard, the car has had a fair bit taken off and what with the way the scrap cars get shoved about with forklifts etc. it was difficult to see the original damage. I only had a few pics of the car to go by.

On closer inspection I found this worrying sight around the E-brake drum section of the rotor:
(the cracked section is actually leaning outwards)





Is this number any indication of the manufacturer of the rotor, aftermarket or otherwise?



I'm going to buy a replacement rotor, but I was wondering if anyone has seen anything like this before happen to a nearly new rotor? Its as if the parking brake cracked it.