I was looking at the Shimano Curado 100B schematic and it says that BNT60 (spacer) is an optional part.
What would be the advantages of having one vs not having one? Ive noticed some curados I have worked on have it both ways.
Shims and spacers are usually to correct for minor variances in machinework.
turn the reel upside down and slip the pawl into the line guide. Now look at the top and see if it's flush with the edge, If it's flush, you don't need the spacer. If it's down a bit, you may need one or more spacers. They keep the pawl in the worm track and prevent premature wear. You also need to look inside the pawl cap to see if it has a flush bottom or a built in spacer. Some have built in spacers already. the Shimano does not have a built in. Also the spacer will often be stuck inside the pawl cap and it's easy to miss, then loose during cleaning.