Just purchased our 13th boat, a 2000 model year Cat310, (a Dock Condo for our aging years), after four decades of race boats. As I work my way through the maintenance upgrades needed you will notice from the attached photo the "HappyBuy" Chinese diesel furnace fuel pump is leaking, but that is not my question. I will replace this accident waiting to happen with an Espar or Webasto and would probably place on top of the holding tank as existing heater is, but would like to know if the cabinetry marked with a question (?) around the holding tank is stock Catalina , or has some PO 'boxed in" the plastic holding tank ?