You cannot determine the maximum towing capacity without knowing the specific trim level and options of the van.
To find the exact towing capacity for *your* 2004 Chevrolet Express Cargo van, you should:
* Check the sticker on the driver's side doorjamb: This sticker lists important information about your vehicle, including its towing capacity.
* Consult your owner's manual: The owner's manual will have a section detailing towing capacities for your specific configuration.
* Check the Chevrolet website: While the exact specifications for a 2004 model might be hard to find, searching for "2004 Chevrolet Express towing capacity" may yield some helpful information.
Without this specific information, I cannot provide a definitive answer.