I got up in the attic and looked. The bolt-on pulley is still here and at some point I had cleaned it. The size will match exactly the size of pulley on your balancer now, that being about 6~6.25". As I said, I used this with no problems at all with a York compressor for years. It is cast iron, runs a 3/8 inch belt and was balanced (apparently when it was made). The pulley on the York was a 5 inch pulley and the pulley on any of the Sanden/Sankyo/etc compressors you get today will also be a 5 inch pulley. You will need to go buy the two bolts and two lock washers to hold it on, but that won't be a big trick. $25 delivered and I won't be offering this in the parts for sale section because it is yours if you want it.
Now having said this, you know there are adapters out there that will let you run an alternator and a compressor, don't you? The compressor you get will have a 2 groove pulley (if you get one of the newer Sanden/Sankyo/etc...and if you're using the old York, please rethink that idea carefully--it was an antiquated pos and you will need an idler pulley to adjust your belt as that compressor sat on a flat plate or sideways on a flat surface and had no provision for adjustment...plus it would not be able to handle today's refrigerant pressures). The way these work is you buy a belt to go around the balancer pulley you now have, the water pump and the pulley of the compressor. That belt will probably be 44 inches. Then you buy a belt to connect the compressor to the alternator and that belt will probably be 34 inches. Hint: buy the belts at an ACE hardware store. They sell belts made by Mitsuboshi (not Mitsubishi) for farm equipment and they're less expensive and good quality.
Just let me know on the pulley.
