1978;truck fuel sending unit screw heads

Rounded off.Tried a drill screw extractor called grabbit.no go.Any ideas.

Drill the screw heads off with a drill large enough the take the heads off without drilling in the threaded part of the screw. Remove the sending unit and there should be enough screw to get small vise grips on.

Take a dremel to the sides of the screw heads and make two flat surfaces across from each other. Grab the screw by those flats with a small vise grip. If all else fails, grind the screw heads completely away, remove the sender, grind the screw stubs flush then reclock the new sender and drill new holes. There's a metal ring cast in the plastic around the sender opening.

I wouldn't recommend using a Dremel around a gas tank because of sparks. But if you are super careful it might be ok.