A Chevrolet C/K truck.
The Chevrolet C/K was a model of truck made on Earth by Chevrolet during the mid to late 20th century.
In 1986, Gillian Taylor drove a Chevrolet C/K from her home to her job at the Cetacean Institute. She later drove Spock and James T. Kirk to Golden Gate Park in her truck after they got kicked out of the Institute. Taylor claimed to have a tire iron behind her seat of her truck. (Star Trek IV: The Voyage Home)
The model shown represents the body style introduced in 1979.