I have the same diff and tag...... I have asked Holden and they have said that it is an LSD? and , just to confirm this I have jacked up the rear of the vehicle and turned one wheel and the other turns, and with a mate on the other both still turn? This is a Limited Slip Diff in my books, or as we used to call them, a "slippery diff". I'll sent a PM to Holden Mechanic and check, but I'm sure as hell, the tag with "high performance" is an LSD?
You have an awesome single spinner with a 2.87 ratio. Prob the biggest peice of crud that Holden have released in a car since the banjo. The "optional" LSD lasts all of a few months stock and needs to be shimmed. Find a Manual diff (3.46's) from a LS1 (VXII to VZ) as they have the LSD and you will transform the car.