Early Swing Arm bikes don't have the spacer. It was fitted when the fully enclosed chainguard was introduced, moving the primary case away from the crankcase to make space for the fixed front part of the chaincase.
Primary chain alignment takes some sorting with two different clutches used and variants of clutch/mainshaft adaptors available. The inner primary chain case invariably needs a home made spacer (where it bolts to the frame) to avoid strain on the casting. All covered elsewhere in the Forum.
Swarfy.
