NOTICED SMOKE BILLOWING OUT FROM UNDER THE BACK OF THE TRUCK AND IMMEDIATELY PULLED TO THE SIDE OF THE ROAD. WITHIN SECONDS THE CAB WAS FILLED WITH BLACK SMOKE AND THE FLAMES BROKE THROUGH THE DASHBOARD. THIS HAPPENED SO FAST THAT THERE SEEMED TO BE NO FIREWALL BETWEEN THE ENGINE AND THE CAB OF THE TRUCK. THE FIRE WAS SO HOT IT MELTED PIECES OF THE TRUCK, AND THE TIRES.