There is a terribly stamped label on the back, I might try to do a rubbing on when I get a minute. Found it! Metos Sauna Model NO. MSPO.
The good news is it is a single-phase heater. It was connected to a double pole 40 amp breaker with the Ground and Positive lines pigtailed in the Electric Box.
Here are some pics.
That being said I'm totally stoked about the Cedar I painstakingly removed. The Boards are 10 in. wide and the sauna was a perfect 8x8x8.