I'm a new guy here so bear with me. I am updating our guest bathroom in our 1973 house. I live in south Florida in a one story house built on a concrete slab. I have removed the tile in the shower to discover a drain that doesn't resemble any drain I've seen in the local hardware stores or online. This drain pipe appears to be a 2 in cast iron pipe. However, I can not determine if this shower has a pan or not. The flange in the picture does not appear to be the upper part of a typical 3 piece drain as it does not screw into anything but the strainer was screwed into it. It appears it has been attached using lead solder. My dilema is to what extent should I demo this shower? I am leaning towards a complete demolition. In other words, ripping out he walls, that appear to be plaster with no cement board, and chipping out the floor to the slab and put in a new pan. I haven't noticed any leaks in this shower but a local plumbing supply store looked at the picture and said I probably don't have a pan. How can this be? Almost 40 years an no leaks? My big question among many is can I remove the flange in the picture and somehow cut the pipe down to install a 3 piece drain so I can put a new pan in? Do I need to graft in some PVC or can I use a CI 3 piece drain on the old pipe? Is there a coupling that will accomplish this with no leaks if I go PVC? Better yet, do I have to do any of this and get away with tiling over where the old tile previously laid and pray for no leaks in the future. One of my concerns is that if I do have a pan, it is lead and after 40 years if it's not leaking yet it will be soon. Thanks for your help.