1965 AC Compressor Pulley

My car came to me with a single groove pulley and what I believe to be 67 & up alternator brackets.

65 AC cars used a special cast iron alternator bracket. I believe 66 AC cars used the same alternator bracket as the 65 and 66 non AC cars.

My car was built in late June of 65. I wonder when the changeover occurred to the 66 single groove setup?