Why is my fuel gauge, at instrument panel, "NEVER" indicate correct gas amount?

That's well and fine 'IF' the tank sender is working properly! TESTING is the ONLY way to know for sure!!!!!!!! WOW!

A simple way to see if your fuel module is malfunctioning is to observe whether or not the low fuel light intermittently lights up when gauge is fluctuating from full to empty. If the gauge gives erratic reading, but never illuminates the low fuel light, then the cluster stepper motor is the culprit. I'm somewhat familiar with these defective Switec stepper motors as I've been repairing GM gauges for 5+ years for individuals and several GM dealerships in my local area. WOW!!

LMAO!!... Ever use a real scanner??..... After you have been doing this for 40+ years.... get back to me!!

Have you ever actually opened up any gauge cluster and actually repaired the circuit board or were you just trained to use a scanner and end up just replacing the cluster like most technicians? You're obviously are a dealership man. Yours is the same reaction as when I walk into a dealership maint. bay and make repairs to components the dealership techs were never trained to do. LMAO!!