WARNING: This page is about a different car, the 2020 Buick Regal and 2019 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
Courtesy of GENERAL MOTORS COMPANY
Callout
Component Name
1
Heater Inlet and Outlet Pipe Bolt [3x]
2
Heater Inlet and Outlet Pipe
3
Heater Inlet and Outlet Pipe Gasket Procedure Remove and DISCARD the gasket.