Ted, the module that Rod posted is a constant current module, not a constant voltage module, apples and oranges. Rod's module is a take-off of my passenger car lighting module, it's only 1/2" x 1" and about 5/8" high with the tab folded. The module you posted is much larger.
I also wouldn't be considering linear supplies for that kind of power, that will dissipate a LOT of heat. Exactly what use are you considering for the supply? That one is too big for most rolling stock applications.
