Yes, that's a ratio changer for the speedometer. If you watch the speedo during a rear end shift, you'll see the needle change positions as soon as you move the splitter knob- - - -even before the differential actually makes the shift.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!