On the left is the front view of the t-stat, this is what you should see sticking out of the t-stat housing pointing toward the front of the car.

On the right is the back side, with what I call the "foot plate". This goes into the t-stat housing toward the cabin.

The arrow is stamped on the main body of the t-stat (just obscured in the left picture, and just barley visible in the right picture). The relative orientation of the arrow and the o-ring tab are roughly correct in the pictures.