If you have been looking for a 100% correct master cylinder to finish off your 1967 Corvette, look no further. No more sleeving, or looking around for a core, buy it new. These GM Licensed Delco Master Cylinders look, feel, weigh and perform exactly like an original because they are 100% Correct GM Licensed units. Features factory correct 5455509 casting number, DC Stamp, Twin Bleeders and 1" bore. Even the caps are right, with correct "Service with Delco Parts & Use Delco Brake Fluid" markings. GM Part# 5458831. Check your judging manual, these are the real deal!