The topic of other parts of the IND second system came up recently on nyc.transit. Someone brought up the rumored IND Prospect Park Line (today's F train in Brooklyn) to Staten Island. I dug through my archives and lo and behold from the 1939 plan, drawing 72-395 we find:
This is a reduced version of the two half drawings, trimmed to fit side by side in a web page. If anyone wants the Full 7+MB (zipped slightly) files, please use this link.