[quote quote=12941]The reality is that you can use a drum brake MC for front discs so long as 1) it has the correct bore for the application, 2) you remove the residual pressure valve that is in the outlet port to the front brakes, and 3) you understand that the smaller reservoir for the front brakes will require more frequent checking of the fluid level.
There is nothing magic about a master cylinder for disc brakes. The calipers neither know nor care what it looks like. All they care about is the piston bore and stroke.
Now why is a dual m/c needed? I know ford has a single m/c for power disc/drum. just asking if GM had one.