CBS is actually scanning the 35mm original camera negatives for many of their classic shows, including GUNSMOKE, OUR MISS BROOKS, PETTICOAT JUNCTION and others.
35mm prints are rarely used by anyone, primarily because so few exist. Those that do exist of color shows are likely faded. And making new prints would cost more than scanning the original negative in HD.
Many of the low-rent distributors do use 16mm prints for their transfers though.
Interesting. I've always wondered how they do it. I don't want to derail the thread but can you expound on how the process is done? I have software on my computer to restore music and it's always piqued my attention how they do film.