WHILE TRAVELING 60MPH HEARD A NOISE. NOTICED SMOKE IN REAR MIRROR. TRIED GETTING OFF FREEWAY BESIDE RAMP. PARKED VEHICLE. VEHICLE CAUGHT ON FIRE. TOWED TO DEALER. INFORMED REAR DIFFERENTIAL HAD GOTTEN HOT WHICH CAUSED FIRE. HAD BEEN TO DEALERSHIP SEVERAL TIMES COMPLAINING ABOUT DIFFERENTIAL.*AK