Master cylinder kit for tin tank clutch master cylinder. Suits tin tank with 0.75" bore with a groove around the body of the master cylinder. This kit also suits the late plastic tank clutch master cylinders with small cap (part GMC1008).
Note that when compared to the no groove type kit (50641), in this kit the two smaller seals both have a hole in the middle.
Cross reference: 52251 / K7753X