Finished the flush today. Nothing but brown water came out. Shoved a water hose in the upper coolant hose, turned on the heater, and flushed everything out until the water ran clean. Did the same for the radiator and flushed a bunch of rust out. Changed the thermostat out and put the jiggle valve at 6 instead of 11 like it was. New radiator cap. All new coolant. Feel much better about it now.