You could do all that welding mess, or you can take a grinder with a cutoff wheel and cut the washer part off the outside of the bolt. This will relive the pressure on it. Then buy a new bolt.
um NO if red loctite was used ONLY heat and LOTS of it will make it come loose
and i dont know how you would get a grinder up in there to cut the "washer" part off anyway, the motor is still in his truck