are you sure you don't have a black h2o tank? we just (last night) ripped up our "bathroom" and come to find out there is a really ugly (yellow, orange, red) tank under a plywood frame that the toilet, or what is left of the toilet, is mounted to. If you don't have one, you might have had the same type of set up that we do on our trailer. See my thread "bizare toilet set up" for the answers I received when trying to figure out what happened to the toilets back in the day. We are going to rip ours out and put in new tanks so if we or anyone else find a way, Im sure we'll all share with you.