Where is the thermostat located at on my 1998 cadillac catera

Hello, Dave here, contributing to RepairPal and providing expert advice since 2010. First, how have you determined that the thermostat is faulty? As far as location, I would follow the coolant hoses and pipe from the radiator. It's underneath the intake manifold. The intake must be removed to access it. https://repairpal.com/auto-repair-near-me Click the link or call us at 877-913-1554. We'll gladly find you a certified RepairPal shop in your area.