Thermostat location and replacement?

Hello,

I have attached thermostat replacement procedure on your GMC Savana 4.3L V6.
A thermostat usually fail in 2 different ways.
First it could be stuck closed. If it is stuck closed the engine could overheat, as it prevents coolant from flowing thru the radiator to cool down.
Second it could be stock open. If it is stuck open then the engine may not reach its operating temperature. When this happens the heater will not blow enough hot air.

Here are couple of helpful articles:

https://www.2carpros.com/articles/how-an-engine-thermostat-works
https://www.2carpros.com/articles/replace-thermostat

Video of thermostat replacement procedure:

https://youtu.be/EZ4luHCzBeo

Please let me know of any questions.

Thank you.