Doug, Mike; Here are photos of mine taken after I removed the toilet and as I replaced it. You probably see the same thing that you saw with yours, Doug. My PO had also glued the floor flange (if you look closely you may see the outline that the removed flange left) to the tank. However in my case it came off easily. Since I was replacing my tank as well as my floor my new flange (second photo) screwed to the tank and makes a very secure anchor for the toilet. A side note: I coated all of my new floor plywood with fiberglas resin....both sides and edges. I figure that this area will always be prone to water leaks and spills and I don't want to do this again. I have built 4 darkroom PLYWOOD sinks in 30 years and coated them with F.B. resin and have never a leak. Glad to provide more help.
Neil and Lynn Holman
Kirk Creek, Big Sur, Ca. coast.
1966 Trade Wind
1971 Buick Centurion convertible
1969 Oldsmobile Ninety Eight