Someone can correct me if I'm wrong, but depending on what kind of build you are wanting to build, I would assume that this truck would have been offered as a glider. Though it unlikely, the possibility of a glider finding itself with a 3408 is possible, especially in these parts of the woods. There was an owner operator here about 10 years ago or so that bought a new W900 glider and managed to put a non-computerized 3406 in it. If you're wanting to represent a specific company, you may attempt to find out what kind of engines they ran. If you're wanting to build a truck finished on the assembly line, refer to the great advise already given. If you're wanting to be different, the sky is the limit.