the coolant leak you put a diagram of it online, what is the plastic part and where do I get a new one

I have a coolant leak where the pipe comes out of the engine that goes to the overflow tank, and the pipe that goes to the heater hose has split. I used JB Weld to put a new pipe where the over flow hose goes, and also on the split pipe, it is plastic. What is this called and what part do I need to get to replace the whole plastic mess? It is where the little pipe comes out and the big heater hose comes out.