VW Bug, Super Beetle, Ghia and Thing Master Cylinder Stock Replacements or 4 Wheel Disc Brake. Stock replacement master cylinders for stock drum brake systems or if you have upgraded to disc brakes master cylinders with a larger bore. Bug, Ghia and Thing have basically the same chassis and the master cylinders are the same for the model years except Super Beetle these are different. 1950 to 1966 master cylinders for use with front disc brakes and rear drums has a larger bore with residual valve removed and needs a Bus style screw on reservoir or adapter. It is recommended to convert 1958 to 1966 models to the 1967 to 1977 style master cylinder for 4 wheel disc brakes. It is also recommended to upgrade the stock 1967 to 1977 models or 1971 to 1979 Super Beetle master cylinder to the larger bore master cylinder when converting to 4 wheel disc brakes. Also available is the rubber grommet for the reservoir inlet on 1950 to 1966 stock master cylinders. DOT 3 brake fluid only.