* Check the vehicle's sticker: Look for a sticker on the driver's side doorjamb or the glove box. This sticker will list the GVWR.
* Consult the owner's manual: The owner's manual will also specify the GVWR.
* Use the Ford website (archived information may be needed): While current model years are readily available, finding information for a 2005 model might require some searching. You may need to look for archived specifications.
Without knowing the specific configuration of the truck, I cannot provide a definitive GVWR.