I had this problem on my 95. The heater core is in a plastic case with a small drain hole below the inlet and outlet lines. If the core leaks, any fluid lost will drain out the hole and be deposited on the ground directly under the firewall. It was not that difficult to replace the core. I did it in a few hours one Saturday afternoon on the driveway. I had to remove the center console and use a little persuasion to get the old one out. The new core cost $65, but the toughest part was finding it.
