Yes, I know that your tractor is the diesel version, not the 322 like I have -- just wanted to share the info that is common to both (the PC2149 covers the frame, body panels, driveline, wheels, etc. in addition to the gas Yanmar engine)
I saw that the 332 parts catalog did not show this spacer, and of course the fan itself is listed as a different part number (M89184 versus the M802453 shown for the 322...) so perhaps that is part of the reason no spacer hub is shown/needed.
Usually the squeal relating to the fan is from the blade *TIPS* touching the shroud, and that is often caused by sagging motor mounts at that end of the engine. Do the tips of your fan blades look like they are getting abraded by the metal shroud?
If the squeal is from a misalignment of the drive and driven pulleys (in other words the belt is not running in a single plane...) you should be able to see any such offset that would be significant enough to cause a rubber squeak. The hub used on the 322 is about as thick as the belt itself, so if the pulley needed such a spacer the alignment would be obviously wrong...but that would imply the spacer would need to go between the pulley and the pump hub, not between the pulley and the fan.