Vehicles and Era's

[Jersey pete]

This is a bit perplexing for me and am not sure if the change is possible. I wish to change the vehicles on my roads in a route i have completed based on a part of Derby UK. I want the route to be set in the 1950s and when i place roads onto the layout it produces modern cars I used to be able to change this in Trainz by changing the region and then removing the vehicles but cannot seem to find what the region Kuid is in Trans Dem nor the cars used in the default area.