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.

I think after a good night sleep and reading other posts a solution came to life for me. I went back in the morning and look another look. This time I started to wedge in a putty knife, then a small chisel around the ring to better understand what the deal is. There still was enough rust that it was hard to tell, but I could definitely see a pipe coming up and this frange was most likely attatched to the pipe and not bolted into the floor, In any case I cleared the debree from around the whole of the flange and was able to see that the tie down bolts just slip into a slot in the flange. Phew I got those bolts in and thanked my lucky stars I didn't go get tools to cut that flange out. I am going to shim the toilet where needed, bolt her down and culk around the edge and call it a job done.