That is a stainless version of a Stumps smoker. He used to make them for Viking, but I'm pretty sure he no longer does. Unless you can find one in stock from a while back you may not be able to get it (If you look at the Viking website it shows it's discontinued).
Stumps still makes smokers (and damn fine ones I might add). I would look at both Stumps and Superior smokers (both are made in Georgia), and there are other gravity fed models out there too.
They are different animals from the WSM and there has been lot of fine bbq come out of gravity fed models (I wish I had one and almost bought a Superior last year).
There are videos on all of these (Viking, Stumps, and Superior) on YouTube. If you have not seen them, take a look as they give a good overview and even operational details on how a gravity fed smoker works.