I just put in my dash harness and there is a plug towards the end orange yellow and blue for a heater resistor to be plugged in under the dash. I know there is a heater resitor on the engine side, can anyone tell me where this plugs in or maybe it does not thanks mike

If you have a heater resistor under the hood then you have an A/C car. If it's an A/C car you don't have a resistor under the dash and that plug goes nowhere.
Tuck it up somewhere.

Its it the same for 1970