Correct there Rex. But at a push any crinkle rear hub can be adapted to fit. The drive splines are the same, as is the bore for the wheel bearing OD. Different wheel bearings and centre spacers are used on the various model ranges.
As for needing two bearing locking rings, the S/A version gets by with just one, the through spindle design being very similar to the Plunger set up. Progress or cost cutting....?
Swarfy.