Rebuilt with a seal kit. The bore looked pretty bad and crusty. Used a piece of emery cloth to burnish the bore. That rebuild was good for about 18 months and started failing at an inconvenient time (i.e., financially poor student). So, I rebuilt it one more time and immediately bought a new master cylinder. The new one was installed within a month and was in the car when I sold it in early 1980.we need clarification....... you actually rebuilt a pos master cylinder? or did you replace it?