Well Tempered Classic-round or square motor?

I just received my Well Tempered Classic and I am trying to tell whether it is the round vs. square motor version. The bottom and top plates are square (they fit into the area carved out for the motor. } Sandwiched in between those plates is a round motor! I guess I think that I have a round motor version. If in fact this is a round motor version, I understand they had two different round motors. How do I tell which one it is?