Replacing the coolant line to the heater core.

Right next to the master cylinder, there is a plastic piece where the coolant line to the HVAC heater core splits into two lines. When I originally looked at the part, I assumed that I would just have to replace the plastic T. The smaller line that trails off below somewhere below the master cylinder is actually molded into the replacement part. How do I get to this lower connection? Do I have to remove the Master cylinder? I think I must be missing a step that would give me access to these lines.