引用自 Bomber Bird：

I didn't know where to put this, but I figured posting this as a discussion was best.

I was curious in whats to come after you release all of your planed mods. I do have two ideas, both fictional USRA packs.

Vintage Pack

This is if the USRA was formed earlier or the following locos stayed around longer...

4-4-0
2-6-0
2-8-0
2-10-0
0-4-0
2-6-2

More possibilities could include...
2-4-4-2
4-4-2
4-8-0

Modern Pack

Perhaps the USRA was formed a little later with modern classes like...

4-6-4
2-8-4
4-8-4
2-10-4
0-10-0
4-6-6-4 (Simple Articulated)

Additional options include...

2-6-6-4
2-8-8-4
4-10-2

I'm not forcing you to add them, just suggesting.