Heater Box Assembly for 1965-1966 Mustangs with a 3-speed heater motor.The heater box assembly consists of the front and rear casings with doors. This is a factory type fiberglass two piece heater box/heater core casing. The heater box is a pre-assembled unit which includes the gasket and all seals. The heater plenum attaches to this assembly and directs warm air to the car.
Works as a replacement for my old, cracked heater box. Fit is sub-par though; the heater plenum screw holes don't line up with the holes on this unit; as well, the supplied screws for the heater cable brackets are too short and had to be replaced.
By Bill Tumas: We’re here with a replacement heater box assembly for your 1965 through 1966 Mustang. This heater box assembly comes ready to install in your '65 through '66 Mustang with three speed heater. All of your seals are already in place, as well as a resistor for the three speed heater. It includes the bracket, as well as the seals for your heater core. It comes with all necessary hardware to mount to your fire wall and to your heater motor. This heater box assembly is the perfect choice for replacing the damaged original heater box on your '65 through '66 Mustang.