[HayZee518]

The overflow tube is part of the flapper seat so it needs to be removed. Go to your big box store and get a new tube, two brass closet bolts, brass nuts and rubber gaskets, a new tank to bowl seal [soft rubber neoprene] it all should come with the necessary gaskets and new plastic nut. the inlet valve is called a ballcock. if its all really corroded you may need a hacksaw with a 28 or 32 tooth per inch blade. a dremel motorized tool with an abrasive cutoff wheel will help considerably because the nuts under the bowl lip are recessed. best to cut the bolts off inside the tank. you really don't want to use a chisel here.