Within the service manual PDF, IIRC, Holden only recommends the Hoist lift points or the scissor jack sill points for raising the car
( I‘d drop the section from the page 91 of the manual here but I can‘t since Books on my iPad crashes when trying to navigate the workshop manual PDF and I can no longer cut/paste from the PDF as I once could… All this occurred after one of Apples updates
)
They make no other recommendation on lifting the car by the diff (though many mechanics seem to do such). I don’t like the idea of resting the car on the diff bushes which are designed to cope with driving torque rather than vehicle weight...
The front cross member looks hefty enough but again Holden doesn’t recommend it as a lift point. A few vehicle brands have gone to the trouble of actually welding a steel cup on the bottom of their front cross member specifically to mate with a trolley jack and they do recommend this as a lift point… but just because one brand allows such doesn’t mean that it’s 100% ok to do the same on another makes…
I just wish GM/Holden would come clean and clarify whether the diff or front cross member can be 100% safely used to lift the rear or the front of the car…