Originally, the 70 Duster was equipped with an A/C system and I do not want to re-install all the A/C parts back in. I'm told the hole position in the firewall will not accept a heat only heater box, so I want to install the heater delete vent box instead. Worst case block off the hole.
I did not install the heater box back in my 69 Dart and it's nice on warm days to have air blowing into the car. However, on cold mornings/fall days is in Michigan it's a bit cool.