some Duster gauges not working?

IMHO. When both temp and fuel gauges don't work, it's the IVR, check the input voltage to one of the guages, should be in the 6v range or reading on a digital meter between 3 and 10 volts. A test light will also go from dim to bright if it is an original mechanical ivr.

Lastly if you do ground the sender wires and turn the key to on. If you see movement be ensure to turn off before it gets to about 1/2 scale or you could burn out your guages