And for another FWIW, my son and I are going to be taking one of the MC's you show OUT of his disc/drum system that was on the car when he got it. I suspect that since it is for disc/disc, it has no residual valve for a rear drum system. It is showing the signs: you drive for a while and put the brake pedal down and it goes a lot further to the floor than on subsequent pushes. (If you drive for like 5-10 seconds and put the pedal down, it does not do this. So it is not acting like air in the system.)
