Hi everyone. I downloaded the original owners manual & the part # for the thermostat isn't the right #. I have the 4.3 Vortec engine & it has 4x4. I know the thermostat needs to open at 195 degrees but the parts store has a few different models. Does anyone have any advice of know where to find the exact replacement?

 

For example, at AutoZone this would be the one:
https://www.autozone.com/cooling-hea...23_140456_1644

 

Thank you. I have the new thermostat. The radiator is about 6 months old but it looks a little rusty inside. Im going to attempt to flush my radiator & cooling system. Ive never flushed a radiator before but Ive downloaded the haynes manual to guide me.

 

If it looks rusty it might be the left-over brown gunk/mud that would occur because of the original form of the Dexcool (orange) coolant. If the system had air in it or was mixed with the classic green stuff, it would form. Today's green and orange (Dexcool) coolants are generally formulated to mix just fine. (I actually tried an experiment once. LOL)

A place where the gunk can hide is in the back/rear recesses of the overflow tank. It has a funky shape at its rear end. I was only able to get it out when I took it out and took it to my bathtub and rinsed it out several times.