Sorry to come in late on this post, but I think I know exactly what you're looking for. They're used by Chris Cakes, which I believe is a franchise. They come up on Google, and there are a few videos on Youtube.
If you can come up with a similar style batter dispenser, the griddle looks like a fairly standard flat-top with the back guard removed. (Vulcan makes a 72" x 33" griddle) The wheels look like they run in the grease trough, but A good welder could probably fabricate a track system fairly easily. I'm thinking something like steel wheels used in garage doors for the batter trolley.