So I am sure this is classic. I went to replace the toilet and when I loosened the screws that hold the toilet down they just broke into pieces, they were very well rusted. The home is ~45 years old. I pulled the old toilet out and scraped the wax off the flange, there were just some very pointy nubs sticking up that used to be the tie down bolts. I did my best to clean up the flange but I didn't see any place where it was bolted to the slab/foundation, I looked down the pipe and it looks like I could make out a slight ridge, so it's like the flange slide down inside the drain pipe. It all looked rusty but I don't plan replacing the drains at this point, since this would be a major undertaking as the slab would need to be cut and who knows what else. I've see the slip on flange replacments that go inside the pipe and use an expansion technique to seal the gap between the pipe and the new flange asembly. My concern is that if the existing flange is there then adding the new one would just stack up and make the toilet sit higher. Is there a relaticly easy way to remove the old metal flange and then slip in this new one with the compression fit inside the pipe. The next part would be how to I attach the new flange to the cement slab?

I was considering an alternate approach not sure how good this is or not. I seen pieces of metal to replace a portion of a broken flange. I am wondering since they are relatively thin if I could some how drill and tap then bolt two of those onto my flange so that I have a solid place to attach the tie down bolts for the toilet.

For now I found that a top end of a two liter soda bottle while looks odd does a good job of plugging the hole in the floor until this is all fixed.