Gauges not working

[62ChevyC60Wrecker]

My fuel gauge is not working correctly; when the tank is full it reads approximately half tank "over full". The sender took a crap on me and I am in process of replacing that; is there anything I should look at while I have the tank out (ground wise) that may affect the gas gauge? A friend of mine suggested the gas gauge may be bad. My temp gauge is also not operational. This winter it put out heat just fine & it would cook you out of the truck. I polished the temp sender with a wire brush and changed the connector and still nothing. Are there any oem gauges out there new in the box for sale??????