How to fix speedometer and gas gauge
4 Answers
Two different types of speedometers back then, a few were still cable driven, if yours is cable driven then you have a bad speedometer head. If it is VSS driven, then you could have a bad VSS or a bad speedometer servo motor. A live data scan will show if it is a bad VSS.
Gas gauge is most likely a sunk float. However, it could also be a bad gauge.
A gas gauge that always is on empty is a bad ground. Usually an instrument cluster ground. If you have an aftermarket stereo, look for the bad ground there first. The fact that the speedometer is involved also points to the instrument cluster ground. Jim