General Motors GM Genuine Parts 15-10412 Engine Coolant Thermostat Water Inlet Assembly

Hard to beat the OEM parts, never even considered any other brand. Fit perfectly and working flawlessly. OEM parts may cost a little more than some replacements but for quality and fitment and function you cannot go wrong.

good replacement

I had bought a thermostat previously from o'reillys a month previous, truck wanted to run 210 normal and 225-230 degrees with AC on. It was supposed to be a 187 degree thermostat as well. Bought this one and compared, night and day difference. Despite driving habits or AC running, and even high outside temperature, my truck never exceeded 200 degrees. And that was with it being 96 degrees ac on and going down the interstate at 75-80 mph. 98 percent of the time it never goes over the 187 degrees. This is the only thermostat to get for your 99-02 chevy silverado. Those have to have housing and thermostat as one piece. Drain the radiator and take the hose off while drain is still open. 20 mins and your done. Oh....dont forget to burp the coolant system, as that will cause overheating too. Water pump installed new 30 days previous. Get it and thank me later. 99 chevy silverado LS Z71 5.3L 4x4.

Nice quality GM genuine part. Purchased this when I replaced the water pump on my 2006 Sierra. Fit and works perfectly.

Just make sure to read the description on which water pump it fits on/ for compatibility. Works great, was easy to install,

Good value!

Solved my problem

Buy this and install when changing your water pump! Easy to install on the water pump

Works as expected