There was a "P&A product information" bulletin sent out dated February 4, 1965.
It was bulletin #3 and it stated :
"Due to the engine differences between the Special, Skylark and Gran Sport model, the 980880
custom A/C cannot be adapted to the Skylark GranSport.
Air Conditioning will be available on the Gran Sport as a factory option only and a dealer installed package will not be offered."
Kinda sums it up .
Loren