Yea,that's a duct alright, return or fresh air, not too sure just what you call it. I have all the plywood cut and fit just need to screw it down,of course I don't have the right screws and it's a holiday so it will have to wait. I have to work on the heater in my car anyway,the blower motor won't go,just had it recored. It would be nice to have heat it's starting to get a little cool.