This Shay is one of at least two running on the Bitter Creek Western Railroad. See: http://bcwrr.org/.

This particular locomotive picture was snipped from about half way down this page: http://www.bcwrr.org/080809.html. A video is available at: http://www.youtube.com/watch?v=d4ArD49L-_M

I refuse to refer to hobbyist locomotives as "toys" – they are real locomotives that just happen to be running on 7.5 or 15 or 16 inch gauge rail. To anybody who says, "Looks like the real thing," I reply, "It is the real thing." And there are more of them steaming now than 3' or 4' 8.5" gauge ever will again.

I now realize that the CV joints are a requirement for narrow-gauge service on a Shay, as the tighter curves require the boiler to swing farther over the trucks as the front truck leads the locomotive around the curve.

Here's a link to a full-sized Shay: [id=178804057]. It likely ran on 3' gauge rail. You can see the CV joints on it as well.

In fact, they might not be CV joints. http://www.youtube.com/watch?v=ok2gyZkLPfM shows what appears to be an enclosed universal joint. Perhaps the smaller locomotives can get by with a universal joint. Anybody know?