Loosen the silicone and older sink with the putty knife.

Remove the older sink.

Remove all of the old silicone using the putty knife.

Add a rim of new silicone caulking.

Add the new sink. Since this one is cast iron, no clamping is needed because the sink weighs enough.

Add plumber's putty to the new drain and insert the drain into the sink.

Once the drain is set in the sink hole, you will want to put the drain together in the following order: rubber gasket, washer, nut. Then, secure the drain to the sink.

Connect the plumbing to the drain. First, connect the tail piece to the drain basket, and then connect the drain line to the tail piece.