1970 Dart Swinger Heater core Removal

If I remember correctly, remove the cardboard glove box, nuts and plate at the fan motor under the hood, remove heater hoses, remove wire connections under dash, remove defrost hoses, and most important remove the long hook in the fresh air box. Arm thru glove box and one under dash it should drop right out.
Above is for non AC cars.
Detroit Muscle Tech has a great resto kit for the heater box.