okay I just took mine apart due to dash restore.... that duct attaches to a small hose that goes to a switch on the dash, and yes its to send air hot or cold to the drive side floor area. the other end connects to the front air port on drive side as well. if your duct are dry rot like mine head over to the hardware store and get plastic vacuum line to replace them ( the kind used for shop vacs), works perfrect. got to give credit to Jon at Motorsports for this idea. if you need pics let me know and I'll snap a few before my dash goes back in.