PICK-UP GAUGE SHOWED HOT. GOT HELP AT NEAREST STATION AND REPLACED LOST COOLENT. SEEMED TO HAVE COOLED DOWN. DROVE ABOUT FOUR (4) MILES AND NOTICED SMOKE COMMING INTO CAB DOWN BY THE GEAR SHIFT IN FLOOR BOARD. IMMEDDIATELY PULLED IN TO A SCHOOL PARKING LOT AWAY FROM OTHER CARS. GOT OUT AND LOOKED UNDER THE PICKUP. SMOKE WAS POURING OUT BY THEN. WITHIN ABOUT 5 MIN. AT THE MOST A FIRE STARTED UNDERNEATH AND WITHIN MIN. THE WHOLE TRUCK WENT UP IN FLAMES. FIRE DEPARTMENT HAD ONLY 6 MILES AT THE MOST TO TRAVEL AND RESPONDED QICKLY BUT IT WAS COMPLETELY LOST BY THEN. WHAT COULD HAVE MADE IT DO THIS JUST BY GETTING HOT? HAS ANYTHING LIKE THIS BEEN REPORTED BEFORE ON L990 FORD RANGER PICKUPS? I WAS TRAVELING ALONE AND GOT OUT SAFELY BUT I WAS VERY SCARED AND COULDN'T BELIEVE THAT IT COULD HAVE BURNT UP SO FAST. AND GOT OUT.*AK