I just uploaded a new Butte Division scenario. The work order is quite simple: deliver 23 empties to the grain elevator north of Great Falls, return with 21 loaded cars. However, at 100 mins + and with some tricky switching moves, this is actually a challenging scenario. And a very scenic one too, as you will be running your hard-working single GP9 into a beautiful autumn sunset.
You can download the scenario from my website, or soon also from the file libraries near you.
Some preview screenshots: