This is an aftermarket 11mm rear brake master cylinder with the 50mm mount holes measured center to center. Finally if yours is ruined you have a new option. This is NOT made by Brembo but appears to be an absolute clone to what was on your later S2, MHR, 851, 888, early monster etc etc.
Ducati Fitment (partial listing):
Ducati 750 Monster : 1996 - 2001
Ducati 750 Monster Dark : 1996 - 2001
Ducati 750 Monster Metallic : 1996 - 2001
Ducati 851 S : 1988 - 1990
Ducati 851 S : 1992 - 1992
Ducati 851 S Tricolore : 1988 - 1988
Ducati 851 SP : 1989 - 1989
Ducati 900 Monster : 1993 - 1999
Ducati 900 Monster Cromo : 1998 - 1999
Ducati 900 Monster Dark : 1999 - 1999
Ducati 900 Monster S : 1998 - 1999
Fits Benelli 900SEI 1982 and other models.......
Verified Purchase
Brembo 11mm rear master w/50mm mounting aftermarket replacement
Reviewed by murphus736 on 03/31/2021
Just installed one of these on my '88 Paso, which, like my '83 Laverda RGS, came with a PS12 - 12mm master. Alas, the PS12 is no longer available, and the available rebuild kits have the wrong piston (rocker type instead of pushrod type). Yes, it's 1mm smaller, but that means a firmer pedal, which really is a good thing. I'm ordering another one for the Laverda. Awesome to finally have a replacement, and it appears to be an exact clone of the original Brembo.