[dewaynep]

I believe those hoses ARE to the rear heater core and the thing they are connected to is the shut-off valve to stop the flow of hot coolant to the heater core when you are running the A/C. Those are probably the most convenient hoses to connect the "T" into so I would go for it. Unless you are trying to reverse flush the system it won't really matter where the "T" goes, the coolant will flow where it needs to. If you are running the engine while flushing the system it really won't matter since you won't be able to reverse the flow of the water pump. I say splice the "T" in and try it. You will need to run the engine so the heater control valves stay open and allow coolant to flow to the heater cores.