This hose busted. It's on the bottom of the water pump. The end that goes on the water pump is a little larger than the end that goes to the heater core intersection.
Yeah, I know that one, it's 5/8" on one end and 1/2" on the other. Go to a good auto parts store and ask to look at their "hose wall", you may be able to find a pre-bent hose that will work.