WHILE TOWING THE MANUAL TRANSMISSION JEEP WRANGLER RUBICON (TRANSFER CASE IN NEUTRAL AND TRANSMISSION IN 1ST GEAR) 4 WHEELS DOWN THERE WAS AN EXPLOSION UNDER THE JEEP WITH A BALL OF FIRE. THE VEHICLE WAS INCAPACITATED. THERE WAS NOT ANY SMOKE, NOISE OR INDICATIONS OF AN ISSUE BEFORE AND UP TO THE EXPLOSION. THIS HAPPENED ON A STRAIGHT SMOOTH 4 LANE ROAD AT 40 MPH.