I think I'll take a potshot at this. Based on the design so far (large firebox, drivers too close to the smokebox to normally be a 4-8-4 or a 4-8-2) and you clearly stating it not to be a 4-8-4, I believe I can safely conclude that it's a Berkshire (2-8-4). Looking at the current overall design again, we can limit the locomotive's region to the Americas. I'll say this is a North American engine due to the at least comparative lack of South American content, just to be safe. I'm also going to be a little more specific by ruling out the Chesapeake & Ohio due to the K-4 being built into T:ANE. I have my doubts as to whether it's a midwestern road, but time will tell. I also have doubts that it's Canadian due to the front of the smokebox. But I will ask: is it Lima, benjaminw?