The diff in the Commodore hasn't been locally made for a decade or so (possibly longer), so unless it's an old BTR unit, it's likely to be a GM Asia diff, which just happens to go under the VE/VF Commodore.

Holden's Engine plant in Melbourne exports a lot of V6 engines - that's been going on since 2004, and prior to that, they were doing the 4-cylinder Family 2 & its many derivatives.

Apart from that, and the likes of Toyota & Holden exporting complete cars, I'm more aware of the smaller tier suppliers, or independent businesses in their own right who are exporting - common names you'd know of would be Harrop, Holinger, and even ARB (albeit a lot of their manufacturing is in Asia, but engineering, assembly & despatch is in VIC).

There's some clever engineering going on in SA & Vic too - some of the world's best performance cars have Aussie sourced components in them, like Lotus, Aston Martin, and even Lamborghini.

Until recently, when the US decided to start subsidising their own industries again, an Aussie firm in Adelaide used to machine the hubs for Harley Davidson - those raw hubs were cast here locally too.
The cost to produce the required level of quality was cheaper in Oz, than in the USA.
Sadly for us, the US government woke up to the issue of offshoring, and made a few feeble attempts to reign it in - offering incentives for local production, to make it more competitive against all the imports. Mainly designed to offset the massive amount from China, but the Aussies fell victim as well.

Lots of the parts of VE and VF are sourced from Korea, not an Aussie car built from parts sourced from small industry anymore like a GMH car used to be.

What about an LH Torana with 4.2L V8 with Aussie built carby and aussie 3 or 4 spd? There may be some minor bits sourced from the US but not many. I think the car is a full Aussie design too not a modified US design.

I still reckon the HQ is not an Aussie design though despite what GMH claimed. Looks very much like a US vehicle never released and adapted for here. It is the most like a US vehicle that we ever had from GMH. The way the front rails are done, the wheel stud pattern, the rear fuel filler, even the door hinges.

I don't reckon it was ever built there, but reckon it was designed as something for there but never built. GMH were given the basic design and adapted it for here. Go and look at how any of the US GM cars of its type were built and you can see the design similarities in the front rails etc. The other clue may be that very few of the parts used on a HQ have HOLDEN cast or stamped into them which is very odd. Not saying it is correct but after having all this pointed out to me it makes a lot of sense.

The LH Torana continued with the original Holden build style though and was designed after HQ.