Clogged Heater Core - Which (2) Lines Should Be Disconnected To Flush?

[TimeTraveler]

I made the mistake of using Bar Leaks Head Gasket Fix and clogged the radiator and heater core. Going to try and flush the heater core and radiator.
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Does anyone know which two heater core lines to disconnect for the flushing process?
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Thanks so much!
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