Aftermarket Coolant Temp Gauge
 

I need to install one to have redundancy and I can't seem to find any definitive answer in the book about where the original gauge cluster sensor is. Is it the Water Thermoswitch that I want to put the new one on? Or is the connector next to the Oil Pressure Sensor the coolant temp sensor? Sorry to ask something I am sure is already covered, but I figure this is a simple enough thing to answer. Thank you, and yes I am going mechanical gauge.

It's underneath the oil pressure sender.

Water temp gauge installation is covered in the FAQ.

Thank you