The early ones were gigantic... you should see the one on the /6 compressor I got the interior AC stuff from... But they are so smooth with the rubber mounted crank pulley, idler pulleys to keep belt slap to a minimum and that big mass. The '68 Coronet 318 does not even change when you turn on the AC. The '70 and later like on the Duster make all sorts of vibration and rumblings as the dual belts are flapping around.
