Manual Brake push rod needed
The little O-ring usually comes with a remanufactured master cylinder, usually I get a MC for a 73 Dart, Drum/Disk, manual.
Manual pushrods are different than power pushrods. Drums/disk manual ones are the same as drum/drum manual ones.
I have one, $25 shipping from NJ. Blasted clean...rust inhibitor coated.
Mike