It is the duct that mounts above the Lighter/Defog unit and connects to the Center AC Dash Vent(#4 on our diagram below) distributing air to the center dash vents. Center Dash Air Conditioning Duct. 1970-81 Firebird/Formula/Trans Am.
93-02 FIREBIRD TA TRANS AM CENTER DASH AC AIR VENT BLACK NEW ONE SINGLE 74935
Late Third Gen Trans Am Center Console
93-02 FIREBIRD TA TRANS AM CENTER DASH AC AIR VENT BLACK NEW SET (2) PAIR 74935
71-73 CAMARO Z28 FIREBIRD TRANS AM BRAKE HYDRAULIC HOSE REAR CENTER H79997
OER Center Dash Vent Housing 1970-1981 Pontiac Firebird and Trans AM With A/C
Trans AM Middle Air Cleaner Duct For 1973-1981 Pontiac Firebird and Trans AM