Hi I find that all pretty odd as I have a Pontiac publication regarding what was new for 1966 and air conditioning was listed as a new offering for that year.
In the cover letter to my latest attempt for find out stuff fromm George he is kind of vague on it and refers to air being available in Chevrolet in the late 50's but doesn't mention anything about Pontiac except to says that only 23 AC options were installed in the Grande Parisienne 2 door in 1966. It was only slightly less expensive than the L72 option at around $480.00 which was a pile of money at that time.
The installation in the 63 looks pretty good though?
