For example, a 1986 Ford F-150 hood will not interchange with a 1986 Chevrolet Silverado hood. Even within the Ford F-Series, a 1986 F-150 regular cab hood might not fit a 1986 F-250 extended cab.
Once you provide the make and model of your 1986 truck, I can try to find information on interchangeable hoods. You can also check online parts databases (like those of auto parts stores) using your truck's VIN for the most accurate results.