You need to locate the heater core under the dash. Find the bolts that secure it to the firewall and remove them. Take off all wires that go to the blower motor. Under the hood you need to take off the hoses that run to the core through the firewall. Then you should be good to go.
take heater hoses off the firewall heater box and unbolt heater box on the firewall and then pull heater box down from under the dash and you will see the heater core inside, replace it in the box and bolt everything back together.
8 hours labor plus $67 for the part.
You can buy aftermarket headers with no heater boxes.
Legendaryautosales.com or paddocks.com
Mercon III Dextron
30,110 fastbacks were made in 67.
Check E-bay or google
== == I have a 67' and I tried Bars Leak first in the coolant system. If that does not work look at the firewall for a plate. Go to a bookstore or parts house and buy a Haynes Manual that is specific to your car.
unbolt it from underneath the dash and pull it out.
about 1,800 RPM.
To remove a torsion bar from a 1967 Plymouth GTX, first, lift the vehicle and securely support it on jack stands. Next, remove the front wheels, then unbolt the lower control arms from the spindle. Use a torsion bar tool to unlock and release the tension from the torsion bar adjuster before carefully pulling the torsion bar out of the control arm and frame. Always ensure safety precautions are taken when working under a vehicle.
reach up under the dash and unbolt the unit and take it out.