I am waiting on my new RB67 Pro SD to arrive (the body + lens at least)--in the meantime I am trying to find the back I want. I want to find a 120 Pro SD back, but those seem to be hard to find at a decent price. To me it would be easier to find the SD back and never worry about replacing the foam light seals. I recently found a 6x8 120 Power Drive back--does anyone now if this will produce clean (no vignetting) 6x8 negatives, OR 6x7 negatives? The manual reads "You can use 6x7, 6x4.5 format, with the light baffle frame mask for 6x8 format mounted on the camera body" To me that says--you can use the 6x8 back, but with a 'light baffle frame mask' you can produce 6x7 or 6x4.5 negatives as well. To me, it wouldn't matter if the size was 6x8 or 6x7 as long as it didn't have vignetting or the like. Does anyone have experience with this?