As indicated by the red arrows in the picture of the evaporator unit (not included) this is the short version tube that connects between the blower motor and the plastic blower motor vent tube mounted to the evaporator housing.
Direct Replacement for 1968-1972 1969 Chevelle GTO Cutlass Lemans 7.4L 454 | ENGINKUHLER Racing Radiator 1970 1971 (3-Row)
4Row Radiator w/Fan For 1968-1972 69 70 71 Chevelle GTO Cutlass Lemans Aluminum
3 Row Radiator For 1968-1972 1969 1970 71 Chevelle GTO Cutlass Lemans 7.4L CC161
HVAC Heater Core For 63-67 CHEVROLET Impala Chevelle GTO Cutlass LeMans Skylark
CC161 3 Row Radiator For 1968 69 1970 1971 1972 Chevelle GTO Cutlass Lemans 7.4L
Gas Tank Mounting Hardware Kit Fuel Tank 1968-72 Chevelle GTO Cutlass GS 6pc