The throttle body from a 1990 D150 with a 318ci engine will work on a 1989 318ci engine. The throttle body is responsible for controlling the amount of air that flows into the engine, and it is not specific to a particular year or model of vehicle. As long as the throttle body has the same mounting flange and throttle bore size as the original throttle body, it will work on the 1989 318ci engine.
