Answer:
Auto tracks, Refrigerator car, Tank car.
Step-by-step explanation:
If I could add any building item options to your virtual train to improve its design the following are some of the ones I will like to add.
Tank Car: Since there will be a steam engine on board, it becomes necessary to have a Tank Car where liquid can be kept or even for the purpose of transportation.
Refrigerator car: This is important so as to enable the train carry produce without getting spoilt.
Auto racks: This and many others like the box, livestock cars are needed when you are designing a train that is meant for transporting goods.