[R-390] Clutch question

[Scott, Barry (Clyde B)]

My "new" R390A has something I've not seen or heard about before.  The clutch spindle has a "stop" collar on it.  This is apparently designed to stop the clutch at a certain depth.  Is this "stock"?  I think it has the splined set screws in it which made me think it might be original equipment.  I seem to recall the manual saying the knob should be set to provide a given amount of clutch travel, but I don't recall anything about a stop collar.

Has anyone seen anything like this before?

73,

Barry(III) - N4BUQ