Gen IV SureFitTM System Features: - Fly-By-Wire fully electronic servo motor controls with no cables or capillary tube to route. - Infinite “just right temperature” air blending - Infinite blower fan speed adjustment (1964-1/2 - 68) - Uses original blower fan speed switch (69/70) - High volume dehumidified defrost mode - Separate high capacity aluminum plate& fin cooling coil - Copper/brass CuproBrazeTM parallel flow heater coil - Mounts behind the dash - Uses your factory system controls with our exclusive Electronic Cable Converters - Flat steel firewall cover panel