I have one of those old stainless steel countertop/sinks that are all one piece (the sinks are separate but welded in). I love it and want to add a garbage disposal, but I cannot get the old drain ring out. It has to come out because the disposal has its own ring of course, where the disposal hangs from. I have heat-gunned the bejesus out of the old one and pried as much as I dare on the bottom, but it won't budge. Anyone have experience with these?