That's interesting about the old C route. My 1948 Hagstrom's IND map does not list the C. Then again, it has a few other inconsistencies such as the HH operating between Broadway-ENY and Court St. The Court St. stub is still shown even though the shuttle that served it ended operation in 1946.
They vary the sign settings on R-1 #100 and R-4 #484; I always see something different whenever I drop by the Museum. I did pose for a picture next to 100's sign box when it was signed up as an A.
P. S. I set my sign box for the emergency C route of 1962. The DD setting will be next.