Starting around 1984, they started doing the "Select-A-Unit" or some crap like that. They bundled what they thought were popular options and the dealer just popped in a couple of codes and the car came built. Kinda like the way EVERYONE on wheel of fortune would pick the same letters, they eventually just automatically included them and let contestants pick a couple more letters. Something of that sort.
They came in different levels. G1, G2, G3 and G4 for the G-body. Each level built on the previous level. For example, G2 included everything in G1 group, plus a few more options. G2 almost doubles G1. Power door locks didn't enter the equation until G3 level, and you also got rear defogger and convenience lighting on top of G2.
Interestingly, the select-a-unit method did not contain limited-slip in any package. This is why I suspect that BUTTload of VIN 9 cars that were dealer ordered didn't come with G80.