Also, the amp is a silver box, maybe 3” x 3” x 1”, with silver fins all around it. You’ll need to be laying such that your shoulders are on the driver’s floorboard to see it, and have a flashlight with you. From that position (looking up), it'll be just to the right of the steering column.

What are you putting in? If you are going back to the OEM radio (which I don’t recommend, good aftermarket CD players are very cheap these days), just look up at the amp and pray that the previous owner used a harness. If so, just unplug it and plug the car’s connecter back into the amp, and you are set. Just leave the harness there in case you want to put in an aftermarket in the future. If they didn’t use a harness and snipped off the plug going into the amp, you’ll have to reconnect the wires which will be a pain in the butt… or put in an aftermarket radio.

If you are going to put in an aftermarket radio you won't need the amp of course, but you will need to figure out which wires are for which speaker. You can do this buy just connecting them and testing them, or you can get on the floor, look at the harness and pull on each wire, then marking the wire that moves in the radio slot.