What is the proper operating temp for a 720?

[xsdg]

Howdy, y'all

I suspect that my temperature gauge is malfunctioning somehow, but I'm not sure. What's the proper operating temp for a 720, where the needle would be in the middle of gauge for a vehicle with a functioning gauge? I have a non-contact IR thermometer, so it's easy for me to tell if the gauge is broken or if it's something like my thermostat, but at this point, I have no idea what the middle of the thermostat is supposed to be, numerically.

[xsdg]

FTR, my temp gauge was fine, and my thermostat was stuck full-open at all temperatures. I finally found the number in my service manual; depending on model, the thermostat is supposed to open at either 76.5, 82.0, or 88.0 degrees C. Given that my truck was idling around 45 degC, and running at 50-55 degC on the highway, it's clear why I was having so many problems :o)