I would print the above diagram. There are obvious items you can eliminate right from the start. Heater core, radiator, EGR cooler, etc. From there I would look at your car and determine if the part is attached to the engine or not. If it is, those are shown in the diagram as attached to the block. 4, 16, and 17. You can also eliminate the check valves and such. It only leaves a handful of items it could be. You would need to compare the hose connections of what you do know and really should help determine what that is.