If you need information on pulleys, look at the Illustrated Parts Index 1973 on Vikki's site and click on the Pulleys and Belts link. Scroll to the diagram that matches your engine (6 or 8 cyl) and accessories.
I have a 67 8 cylinder with A/C and power steering. According to the diagram, the crank pulley is #22, an 8", 3 groove pulley. My car actually has the setup listed for a '68 cyl with A/C and power steering. Also listed as #22, it shows a single 7 5/16" pulley for the A/C and an 8" 2 groove pulley for the other accessories. I don't know if mine has been changed, or what. There is a thick rubber ring that fits between the single and double pulley, presumably to dampen vibrations.
