A sample from the products for the Thermostat - Water Pipe include: Water Pipe,upper, O-ring 53.8x3.1, O-ring, 21.9x2.3, Wire A,guard.
In this schematic the "Bolt,flange,6x25" is used most often.
The Thermostat - Water Pipe assembly is constructed from several parts from which the Thermo Unit Assy is the most expensive.