PREMATURE RUST THROUGH OF FRAME. WELL MAINTAINED VEHICLE BECAME UNSTABLE. UPON INSPECTION, FRAME HAD RUSTED COMPLETELY THROUGH ON DRIVERS SIDE, DETERIORATING ON PASSENGER SIDE. FRAME IS FLEXING AT POINT BETWEEN CAB AND BED ENOUGH THAT REAR OF CAB HAS CONTACTED WITH BED. VEHICLE UNSAFE TO DRIVE HOME THREE MILES AS FRAME IS NEAR SEPARATION, REAR SPRING HANGER IS CLOSE TO SEPARATING. UNACCEPTABLE/DANGEROUS MANUFACTURING/PREPARATION OF FRAME BY TOYOTA. *TR