On a 2004 Ford Escape 6-cylinder, the catalytic converter is typically located
underneath the vehicle, near the engine and before the muffler. Because of its heat, it's usually closer to the engine than the muffler. To be precise you'll need to get under the vehicle and trace the exhaust system from the engine back. The cat converter is usually a larger, cylindrical component in the exhaust pipe.
Caution: Working under a vehicle can be dangerous. Always use jack stands and follow proper safety procedures. The catalytic converter gets extremely hot even after the engine is off, so allow plenty of time for it to cool before working near it.
