Look at This:

From Southern Brooklyn Scrap Book

This great photo was taken in 1941.  It shows that the incline to the IND subway to Church Avenue was in place and some of the steel structure was in place, but no steel structure was connected to the BMT Culver Line.  Pictures around 1954 shows that the northbound local IND track was connected to the BMT Culver structure south of Ditmas Avenue, near the signal and workmen shown above.  Notice the trolley line poles to the right on McDonald Avenue.  They were there since the Culver Line was electrified on the surface.  The BMT structure dates from 1919 so the poles were out of service from 1919 to at least 1941.  More to tell you later.