The fifteen Civic 2000 (y) 4dr Lx (ka) Heater Unit component parts are all listed in this schematic.
The most reasonably priced component used on the Civic 2000 (y) 4dr Lx (ka) Heater Unit is the Screw Tapping 5x12.
This HEATER UNIT assembly utilises six Screw Tapping 5x12(s) - the highest specified component.