Take this with a grain of salt as I haven't worked on any of the iron sportster for almost 20 years. However I believe you will need to use the short spacer. The ratchet teeth on the back side of the clutch hub mate to the teeth that's attatched to the kick arm, and if you have too much spacing it will slip right by and you will hyperstend your knee and not be a happy camper. This also happens when the teeth get warm, not fun.