Ask them for the Vehicle Id Number which they can find either on the driver side dash right before where it meets the windshield or on the cars registration (hopefully they do this in canada too)
VIN Decoder That link should take you to the VIN decoder in the FAQ section. Use that to make a final determination on the engine type. Hope this helps
Other ideas: it should display a v6 badge right on the speedometer; 24 valve duratec should also be very obvious right on the engine cover. Since they want to sell this thing they should be more than willing to provide all of this info.