The significance of this is just trying to find one .. not a commercially viable part to reproduce in its factory design but getting tough to find.   GM # is 3963731.

Its the main feeder duct up under the dash on the LHS (US Driveres Side).

With many converted (to RHD) cars being butchered and LH trying to rebuild the AC into their cars it may help somebody out there.

It may have more of an interchange but only knows as a 71-78 Camaro fitment for factory AC cars.