Service and Repair Guide for Yukon V8-350 57L Heater Core with A/C - Page 2434
INSTALL OR CONNECT
1. Heater core.
^ Install the three screws and bracket.
2. Heater case lower cover plate (18).
^ Install the seven screws.
3. Heater core hoses.
4. Coolant to the radiator.
^ Operate the engine and pressure test for leaks.