72 Duster Resurrection
Ok. Just an FYI, if your fuel gage and water temp gage ever are both pegging or going to empty/cold. Then the instrument voltage regulator is on the fritz. The gages you have run on 5V except the ammeter and speedometer. They use a little vibrating points regulator on the back the gage cluster to drop 12v to 5v if it sticks closed they peg, if it sticks open they drop to empty or cold.
I would use a point n shoot digital thermometer to see if the engine is getting too hot. Its a possibility the sending unit for the gage is bad, pegging it out. The sender is on the front of the cylinder head, with a purple wire going to it. The water temp sender is dirt cheap, i think the same part number was used up thru the 90s on chrysler 2.2 and 2.5 4 cylinder and 3.0 V6 engines.