Most Canadian model Minis all had a dual brake system of some sort! The latest models had this square plastic cannister (reservoir). This twin outlet master has separate circuits for front and rear brakes; it's recognised by the rectangular reservoir and small cap. If you are upgrading to a safer, dual line system this is the one to use. Note: Does not come with the brake switch. It has a blanking bolt fitted - the switch is no longer available.

The Mini after 1988 has the brake servo attached directly to the back of the master cylinder. But the good news is that the master can still be replaced by itself, saving lots of money! These new Unipart masters include the sending unit in the cap.
Superceded from GMC242

These are the real thing! Expertly rebuilt in the U.K., these metal cannister master cylinders are available once again. They absolutely look like new!! These are the "short" non-Cooper S master cylinders, but can be used with Cooper S disc brakes.

The GMC167, diagonal split master cylinder is no longer available but at least this kit is still around- at least for awhile.

The master cylinder is the heart of any hydraulic system, and the hardest to troubleshoot. A pedal that can be slowly pushed to the floor indicates the master cylinder is worn. Fluid dripping off either the brake or clutch pedal is a sure sign that the respective master cylinder is leaking. Only one (single line) brake master and one clutch master are currently available, but they will fit any year Mini. Brake and clutch masters look similar, both these later models have plastic reservoirs, and they are NOT interchangeable because they're different internally. See GMC171/ORIG for metal can.

Available once again in limited quantities! Expertly rebuilt in the U.K., these are original metal canister brake master cylinders for the Cooper S. Very rare! The original manufacturer decided a few years ago to discontinue these large reservoir units, replacing it with the standard size white plastic type!

Note: the rebuilt kit for this master cylinder is part no. GRK1006.

This, one of the latest model dual master cylinders, was introduced in 1985. One of the notable features is the failure switch on the reservoir cap. This master is now also the only recommended replacement for all models from 1980 thru 1992, replacing the GMC173/198 and the GMC192/195. It should also be noted that this master has metric unions (top is 10mm and the bottom is 12mm) and the pipes in this front rear split master are reversed from earlier models; i.e., the bottom pipe feeds the rear brakes and the upper pipe feeds the front brakes.
If you are replacing an earlier master that had UNF pipe ends fitted to it, you'll need parts HU9 and HU2.