Yes Hydratrak was introduced with the VR HSV GTS. The chances of seeing it on a stock XH are limited.
A normal LSD transfers power from the wheel that slips to the wheel that grips in an instant. Hydratrak progressively feeds power from one wheel to the other, making for smoother and safer burnouts
. It was dropped from HSV's line-up with the VT, but I believe 300 kW models all use it.