I have old cast iron drain pipes. The bathroom sink has a 2in galvanized pipe that screws into this cast iron pipe. The galvanized pipe is rusting out. Can I replace this galvanized pipe with plastic pipe?

I have old cast iron drain pipes. The bathroom sink has a 2in galvanized pipe that screws into this cast iron pipe. The galvanized pipe is rusting out. Can I replace this galvanized pipe with plastic pipe?

Yes you may replace with PVC. Remove the galvanized stub-out from the threaded cast iron sanitary tee and, after taping the threads with Teflon Tape screw in a PVC Male Adaptor,(see image) and run PVC from that point on. Good luck, Tom