Factory defrost duct for all 1970-72 Chevelle, El Camino, Malibu & Monte Carlo with and without fatory air-conditioning. This is the duct that mounts up against the firewall, inside the car and sits on top of the heater box to allow are to travel out through the dash to the windshield. Comes exactly as shown in the photo below. This new improved reproduction direct bolt-in replacement is made twice the thickness of the original, so it's extremely resistant to the warping and cracking that were common problems with the originals. An Original Air Group reproduction. Replaces GM part #3963756.