3 Girls'
A impact screwdriver usually will get anything out, especially after soaking and heat. If the part left behind isn't a hardened extractor or drill body then you can drill it out. Go up in steps until you get close to the major diameter of screw. A easy out will usually get it out then. You can use Heli-coils if you want to get back to the same thread size, which might be good if the fastener is real specific to your old truck. The very LAST thing I would consider would be building up the hinge area to re-tap. Take your time, out-think the bolt, hold your mouth right and it will come out!

Stuart.