It's an driver adjustable swaybar.
There is a lever in the cockpit with a cable that can rotate the angle of the link /lever ( straight = hard, flat = soft)
I have them (front and rear) in my T/A
Manually adjustable.. here's some old pics of chassis 27 at my workplace, who did quite a bit of the design work (body & chassis & suspension) for the GTS-Rs back then..
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