I was reading about Kenn's build in the "Frame Welding" has reminded me of an issue with my coach. For some reason NRC used equal sized tanks for the black and gray water. Most people produce much more gray water then black. The RVs I have been around always had a larger gray water tank. When using my toter last summer I did have trouble with the gray tanks filling up while the black was nearly empty. Changing tanks would not be practical. I'm thinking about rigging an overflow from the gray into the black tank. Has anyone else done this?