The screen in my SL66 appears to be the original for this camera: Type # 560060 / 64913 Original standard bright focusing screen with micro prism and grid. 10/1966 - 2/1988. Unfortunately it seems dark and coarse and is difficult to fine focus and gage depth of field with. Consequently I am looking to upgrade, preferably to a 45dg split and a super bright fine grained field. I know screens for other cameras fit or can be easily modified to fit, but I am unsure where to start looking and exactly what to look for. I would really appreciate any help and insight you all could offer.