GM cars of that vintage are notorious for weird cooling system designs.

I changed the radiator in a V6 Grand Am (94 IIRC) and got less than a gallon of coolant out. The block drains yielded more, but there was still quite a bit in some of the pipes and hoses and heater core and recovery tank. The actual bleeding process wasn't the worst thing in the world once I got it pretty close and found a good ramp to pull the car up on, and there was still quite a bit of air in it at that point.

But to answer your question, no, it's unlikely it was dramatically low before you changed it.