In putting the interior back in or should I say building from scratch, does the heater and all the duct work go in before the main metal dash or would the metal dash go in first? I'm told that after a year and 8 months that my dash will be arriving soon...
The heater and all the duct will have to go in before the main metal dash

The AC pipe hole on the firewall wasn't on the same spot as the old version cab.