RADIO WAS POPPING DURING DRIVE FROM SEATTLE TO MONTANA. AFTER A DINNER BREAK IN IDAHO, ENGINE DIED AFTER DRIVING ACROSS BRIDGE TO GET BACK ON FREEWAY. SMOKE WAS ISSUING FROM HOOD (REAR DRIVERS SIDE OF HOOD) BEFORE COASTING TO A STOP. VEHICLE ENGINE COMPARTMENT AND ENGINE WERE COMPLETELY DESTROYED - VEHICILE TOTALLED. FIRE CHIEF (SHOSHONE COUNTY, IDAHO) SAID IT LOOKED LIKE THE FIRE STARTED EITHER IN OR UNDER THE FUSE BOX UNDER HOOD. DODGE SENT A FIRE ENGINEER TO INSPECT VEHICLED BUT WON'T SHARE THE RESULTS.