I have found these charts to be useful but not always completely accurate. F'rinstance, I have one that shows "6G2ER" to be the G8 GT and "6G2EC" to be the G8 Base. In reality, "ER" was Base and "EC" was the GT. The one linked above shows Holden to be "5G8". Every Holden I've ever seen listed with its VIN on ebay motors Australia starts with "6G1". So do a lot of US Caprice PPVs, but your SSs start with "6G3". Usually, Chevys are Division "1".
I reckon they're kinda subject to change and alteration.
VIN format is mandated for US vehicles--may or may not be the same for Holden/Australia domestic vehicles, even though Holden is GM.
2011 VIN card - World Make/Manufacturer Identifier (WMI):
2011 Caprice PPV is 6G1 (6=Australia, G=General Motors, 1=Chevrolet Passenger Car)
2016 Caprice PPV is 6G3 (6=Australia, G=General Motors, 3=Chevrolet Passenger Car)
Change from 6G1 to 6G3 took place with 2014 MY--same WMI for PPV & SS
2009 VIN Card data E/C – G8 GT
– G8 GXP
– G8 (base)
Pontiac was assigned WMI 6G2
for Holden-built vehicles (6=Australia, G=GM, 2=Pontiac)
2009 VIN card for US production shows W
engine (LS3) as installed in Chevrolet (1) only. Obvious error/oversight
VIN differentiation for GXP transmission (A6 or M6) not clear from example data, unlike 2015/2016 SS Sedan
2009 GXP listings on eBay/Autotrader – no difference between M6 & A6
M6 - 6G2EP
A6 - 6G2EP
V6 - 6G2ER
57759L235766 (G8 base)
Looks like the only thing you really couldn't come up with for your Holden G8 is RHD....