1965 & 1966 273 AC accessory drive

For the factory AC system on the early A's I've seen two different belt drives. It looks like the earlier ones have two v-belts for the AC compressor and later ones a single belt. I've seen the single belt on some '65 & all '66, possible a mid-'65 change? The '66 has a pulley for belt tension and also a roller that looks like it puts some more belt wrap on the compressor pulley.
Anyone have any additional input?

1965: Note the two belt also run the alternator & are behind the water pump.
image.jpg

1966
image.jpg

image.jpg