I knew it was one of the two, the diffrence in the 88 and 89 are subtle. In '90 they switched to the flush mounted head lights as opposed to the recessed ones on that one.
Woah... Great looking pic, and damn, I wish I had a truck like that! ^_^ Not really the most clever choise though, that takes some gas, huh? Easily like 15 litres/100 km? :D