WARNING: This page is about a different car, the 2002 Ford Windstar, 2001 Ford Windstar, and 2000 Ford Windstar. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Heater Core
Courtesy of FORD MOTOR CO.
The heater core (13476) consists of fins and tubes arranged to extract heat from the engine coolant and transfer the heat to air passing through the plenum.