Will a non ac heater box interchange with an ac box on the firewall on a 1970 nova?

In a 1970 Nova, the non-A/C heater box and the A/C heater box generally do not interchange directly due to differences in their design and mounting points. The A/C box is typically larger to accommodate the air conditioning components, while the non-A/C box is more compact. Modifications may be necessary to install one type in place of the other. Always consult specific restoration guides or forums for detailed compatibility information.