newbie to Horizon170

It sounds as though someone let everything freeze and pulled out the damaged parts and didn't replace them. Not sure though. The Owners manual is practically useless as how it is equiped and no part numbers. Mine is on a Ford Chasis. Mine has a wet shower, a stainless steel kitchen sink and a rectangular fresh water tank about 12 inches square and 36 inches long. Both my holding tanks are located outsid the frame on the drivers side with seperate discharge outlets. I dump the black water tank, switch hose to the grey water and flush the line with grey water.
Good luck with repairs. Just look at a camper parts catalog and maybe you can find what you need. You may even find a parts camper on CL.