Peter, I'd be dropping into the local Holden dealer asking to have a look at their workshop manuals online. I had some luck at Nissan last year trying to identify the part numbers for rear diff splines - asked a few questions and they pulled up an exploded diagram of the diff with all the part numbers and printed out a few pages for me. Might be worth a try?
Make up a story about a minor accident severing a brake line or something like that. Just don't ask for favours on a Saturday morning.
