I have a 501CM and I am trying to figure out which focusing screen is in it. I believe it was bought with the camera new.The screen has a micro-prism circle around a split rangefinder and the camera body serial number code shows that the camera was made in 2004. On the edge of the metal frame of the focusing screen there are two small semi circles cut out on the side that faces you when you look into the camera. Is this an Acute-Matte D screen?