[Smith1000]

I haven't done my brakes for awhile, but I am fairly sure the '97 Lesabre has a thin metal plate that kind of has tangs that spring-locks the plate into place. It goes between the pad and the cylinder. If a brake shop did the brakes, they may have left the plates off on reassembly. Are both sides squeaking or just one side? It is easy to forget and leave the plates off. I have had to pull off the brake assembly again to install the plates after forgetting to put them on.

I would run by another auto parts store and ask them to bring out a box of pads and compare them to what you bought. See what another auto part store has for pads. Do they look like what is on it or what you just bought.
Based on my experience with Autozone, I bet they have the right pads unless they pulled the wrong box.

I have run some cars with discs that are basically shot and they grab and chatter (especially when braking hard), but don't necessarily squeal.