Rear Disc Brakes Or Drums

Are there certain years of aleros that have rear disc brakes and then others have rear drum brakes. I was just in the west coast and all of the aleros i saw out there have the disc brakes, I am on the east coast and have drum brakes.

Im pretty sure the stripped base models have drumz. GLS's have 4-wheel disc.

[Str8tFKNuUP]

I got a GX base model, had no rims of spoiler, but i got disc brakes on the back, it's a 2000. so i don't know.