I am replacing my shower floor and walls with new tile. The home was built in 1977 and the concrete sub floor is in good shape and can be worked with. I will be laying in a new pan membrane, wonder board, and mortar bed accordingly. My concern is the floor drain. I am not sure what it is but am assuming that I will need to replace it with a 2 part PVC drain to accommodate my new floor. I am not sure what I have, PVC or iron, but the drain has the usual strainer screwed in to what looks like a molded brass flange, very smooth and going down in to the drain pipe, no seams or screws. There is a stainless type of O ring looking thing on top of the drain and underneath the strainer that is close and tight under the existing grout line by the drain. What do I do to replace it and how do I get it out? Do I have to chip out the concrete around it to get it out? How will I create a leak free union to what may be iron with new PVC in a close quarter’s embedded type of environment?

Any words of wisdom appreciated. Thank you.