Fuel and Temp gauge issues

"sender not compatible with gauge"

That does not matter. I already posted re: the gauge tester. You set the gauge up with a KNOWN proper power supply, that is a working IVR supplying the gauge, in the cluster just like it was "running" and you substitute a sender SET AT KNOWN TEST RESISTANCE as shown in the photo re: the tester. Those resistances should produce known gauge readings, IE "empty" "half scale" and "full" with the three resistance settings. You get that working. You check the wiring. And then you worry about what the sender is doing.