They aren't a whole lot of choices out there. It's not like you can go down to "Honest Abe's Used Locos" in Denver and pick up a couple that were just used to take people to church on Sundays. (Though at one time long ago you could at least get a used steam loco, sometimes even a new one!)

There was a RUMOR several months ago about D&S looking for a couple diesels in South America. So best guess is maybe a couple White Pass units (will they even fit clearances/bridge limits?) or a couple GEs from South America, but I doubt either could be delivered or placed in service for this summer. Unless EBT or some dealer/rebuilder (McHugh?) has a couple stashed and ready to go?

Sadly D&S is months behind the game of acquiring road diesels or converting engines to oil, at least for this season.