Here is how the GSX packages were offered:
They were all Big Blocks and came with stripes, rear spoiler, grill & dash emblems, hood tach, front spoiler, rallye ride package, quick ratio Power steering, or manual steering, G60-15 Goodyears, 15x7 Chrome wheels, and sport mirrors.
The basic GSX option included stripes, rear spoiler, grill & dash emblems and sport mirrors. (There is at least 1 example that did not include the mirrors.)
The other options, such as hood tach, front spoiler, rallye ride package, G60-15 Goodyears, 15x7 Chrome wheels were all options that could be ordered seperately. Some even came with vinyl tops.
Here are 2 examples:
My 71 Stratomist Blue GSX has a deluxe black front bench with fold-down armrest interior, with an in-dash tach and gauges. (No hood tach.) It did come with G60-15 /chrome wheels, Stage 1 engine, automatic, and 342 posi, but may not have been ordered with a front spoiler.
I also had a 71 350 GSX, with an in dash tach and gauges, (no hood tach or front spoiler), front bench with armrest interior, standard 2 spoke steering wheel, standard ratio power steering, and no rally ride.
So only GSX models came with the factory stripes, even the 71-72 varieties.
Now there are supposedly a few cars out there with dealer added stripes. I have never seen any documentation, but even if I did, they would still not be GSX models. They would only be GS models with a dealer installed stripe package.