Need to change failed 9 month old thermostat on 2004 Intrepid 3.5 l engine. Where do i find it? Must be a long job as they charged me 2 1/2 hours labor last time. Can anyone give me a picture of the location. My son says it's at the bottom of the engine. May have to change a leaking rad too. Will it be easier to change thermostat once fan and rad is removed?

 

Garage says thermostat okay and rad not leaking but diagnosis is bad head gaskets. Mechanic claims coolant being ejected out of reservoir bottle and says they tested coolant and found carbon (100) in coolant. Rebuild is $1600 to $2400. I had added bars leaks to rad some time ago. Would this give that reading he's talking about? Is this diagnosis on the level? Car only overheated for one day and heat went off. I checked fluid early on same day and it was up. He claims no fluid in rad at all when he received car on Monday. Does anyone know about his stuff?