* Condition: The overall condition of the truck is a major factor in determining its value. A truck that is in good condition, with no major damage or mechanical issues, will be worth more than a truck that is in poor condition.
* Mileage: The mileage on the truck is also an important factor. A truck with low mileage will be worth more than a truck with high mileage.
* Options: The options that the truck has can also affect its value. A truck that is equipped with desirable options, such as air conditioning, power windows, and a sunroof, will be worth more than a truck that does not have these options.
* Location: The location of the truck can also affect its value. Trucks that are located in areas with a high demand for classic vehicles will be worth more than trucks that are located in areas with a low demand.
In general, the value of a 1989 GMC pickup truck can range from a few thousand dollars to over $20,000.