The thermostat housing has to be scrounged off a big truck or school bus. It has the same mounting on the head side of the housing as the 235 but the hose diameter to the radiator is differant and it has a bypass hose to go back to the pump. The water pump is exactly the same as a 235 water pump but with an extra heater hose outlet drilled and tapped right next to the normal one. They may be hard to find but you could modify a 235 water pump since the boss is there in the casting.
A school bus is a good place to look because most busses had an extra heater core in the rear with its own set of hoses. Another place would be a marine engine.
