1965 & 1966 273 AC accessory drive

[SSVDP]

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.

1966

 

[65dartcharger]

True!
First groove is for the water pump.
Second groove for the power steering.
Third and fourth groove are for air condition.
In the picture the power steering pump is wrong.
On my 1965 270 wagon assembled June 25th 1965 the air condition compressor have two grooves on the clutch.