Wiring diagram for gas gauge and temperature gauge?

I know on my 73 duster that you can test the regulator by pulling the temp gauge wire off and grounding it.
Then turn the key switch on if the gauge moves the regulator is good.
Turn the switch on momentarly or damage can occur to the gauge or regulator.

This is worth a read.

http://www.moparfins.com/repairs/fuel_gauge_repair/fuel_gauge_repair.htm