I'm not sure what it is called but it's located beneath the oil pressure sender. it's like a tube that goes over another turbo, i'm pretty sure coolant goes throught it. it's located at the back of the enigne

big rubber hose right?... that's your heater hose. It has 2 tabs on it that have to be depressed to make it come apart. I normally just break the fucker and hose clamp the coolant hose directly to the nipple after that.