RE-EDIT: Okay, hmmm... According to a local GM dealership, there doesn't appear to have been a Cutlass Ciera ('89-'96, anyway) available with rear disc brakes. I'm not sure why the Haynes manual would address rear disc brakes if they weren't available, unless they were an option on one of the other A-bodies (Celebrity, Century, or 6000) or one of the other styles (coupe or wagon).
So, does anyone know which style(s) of which A-body or A-bodies (if any) had the option of rear discs?
Thanks again.