I have a 09/2004 build SV6 sedan. I have a small oil drip from the rack and pinion assembly, and chased up an exchange rebuild for it. I spoke with a few rebuilders and it appears the VZ had two rack assemblies. Mine is the "early" one and is not held as an exchange unit by two companies, as it is not the most common one on the market. They rebuild the customer's unit. So maybe the early VZ assembly could be the same as the earlier model Commodores?
In passing, the oil only drips when the car is unused for a long period eg about 3 weeks (away on holidays). On a day to day basis, no oil spots show overnight on the garage floor and no oil is on the sub-frame.