Vehicle traveled down I-65 normal cruising. Had a check engine light illuminated. Code pulled as a P0420 diagnosed for Catalytic Converter. Because of this code, the oxygen sensors eventually went out. Sensors were replaced. Two months later the code for O2 sensors being bad came again. Vehicle was seen by another driver on right side with flames showing under the engine while driving. From there, a noise was heard, seen later as a hole made in the bottom of the cast iron block. Vehicle was pulled to the side of the road. I had gotten out to pop the hood, where white smoke was fuming from. Then I seen flames arise and grabbed all personal belongings fearing the worst (explosion). Flames simmered down after 1 hour passed. Engine was not started but with a hole in the bottom, fear of a rod being slung is scary.