This is actually for a 2008 Explorer, but when I posted the question I got no responses. I am assuming that the rear heater hose routing is similar in the Expedition, so I'll try my question here. I am referring to a heater hose coupling near the spare tire in the rear. I haven't looked in great detail yet, but it appears that the heater hose is aluminum between the Y pipe near the engine and the heater core hose in the rear. At the end of the aluminum heater hose pipe it transitions to a rubber hose which connects to the heater core at the back. Is there a nylon coupling back there that attaches to the aluminum hose on the Expedition? Has any one else had a leak in this location?