[68bird400HO]

Originally Posted by bkmont

I have a 68 manual and power drum master cylinder. My 68 GTO came with the power drum. The manual came off a 68 LeMans .

Both of these master cylinders have 5452310

The 2310 is the non-bleeder version. As I understand, that was intended for manual drum and the bleeder version for power drum. I think they thought the bleeders were needed because of the angle the master cylinder is at when mounted on the booster vs when it is mounted directly on the firewall (level). Like everything else, there are no absolutes with the way these cars were built and I have seen original cars at the yards were this rule did not hold.