The VT rear suspension was a disaster, depending on what you needed the vehicle for. I had to buy a Falcon back in the day because the camber issues of the VT when towing a caravan. Dealership tried selling me a VT saying if they fit HD shocks for me, then towing my caravan would have been fine, I called BS and walked away.
All Commodores upto and including VX, with IRS had a disasterious rear suspension set up. They started improving it with the VY and VZ, but it still suffered with the inner edge wear issues.
The rear toe links fitted from factory with the VX series 11 to VZ helped with wear issues, but the issue faced when aligning them was, they are done with the car empty in the rear....As soon as you started adding weight to the rear, the edge wear started rearing it's ugly head.
You could adjust the toe to help compensate for the camber wear, but it's the negative camber that causes the wear problems
Fitting airbags into the rear springs helped the best, because you could add weight into the rear and inflate the bags when weight was added, so the car sat as it was aligned.
Aftermarket camber kits are a pain to install, and are helpful in reducing the inner edge wear, however adding the dreaded weight into the rear of the car, put you back into the same predicament.
So really to sum it all up, they were a disaster all round