I am very proud to have a very old toilet in my house (so no wise cracks about replacing it please). The tank hangs from the wall and is connected to the bowl by a short length of 2 1/2" to 3" plated copper pipe (I'm currently out of town and forgot the size) extending down from the tank to an elbow coming out of the back of the bowl. The two pipes are connected by a butt joint with a flange on one pipe that fits against the threads on the other. A composite ring came with the replacement kit to fit between the the pipes.
That butt joint between the sections of pipes leaks with each flush. I've tried a variety of fixes, both legitimate and desperate jerry-rigged attempts, to no avail. No rubber rings that size are available at any of the big-box, plumbing, hardware, or salvage/restoration stores in my area.
I'm looking forward to anyone who might have experience or suggestions. Thanks!