Appreciate all the info guys.

I have the RB67 professional S body. That's whats on the back as well. The back rotates from one orientation to another. I don't believe there is any mask under the prism finder and/or WLF. There is a piece of glass that will come out, but I don't think it's a mask. I do see some dotted lines and a red line based on which way the back is turned.

I'll scout around FleeBay to see if I can find a whole back in the 6x7 flavor. I'd like to get the most out of the camera if I'm going to use it.

Yeah, if I know then, what I know now, I would have never gotten this BEAST. I wanted to shoot MF, and found what I thought was a really decent deal on it.

Body, 3 lenses [50mm, 180mm, 250mm], 3 backs, filters, (2) prism finders, suitcase with velvet inserts for all the pieces for 500.00. I bought someone's darkroom equipment, and a WLF was in the deal Kind of getting use to that one though.

Now that I've gotten shoot with or "workout" with this monster, I would have liked to gotten something with a smaller footprint, like a blad or rollie.