I wonder if this lens is one with double coatings?
Dave
My 50/1.4 has a rubber focus ring & serial # 2817671. My assumption that it is the version Mr. R reviewed on his previous site.
(Boy, it's a bugger to focus wide open & get it right.)
As far as installing a split prism.... The span of my most modern camera bodies are a D700 & D7100. (I'm also a big fan of the Kodak SLR/n.)
I often think of upgrading, however it's murky, at best which 24-36mp FF body to employ. Cost & reliability are a major concern. I often consider the D7100 as an over-pixeled, "turd."