My 2003 Trailblazer started making a terrible noise after running for a couple of minutes. It sounded like it was coming from the front of the engine and with the engine creeping up on 200K I was prepared for the worst. Fortunately, it wasn't that bad!
The following things were mentioned in the video but not really touched down on:
I6 Trailblazer belt removal:
https://www.youtube.com/watch?v=a-wSQ...
I6 Trailblazer alternator removal:
https://www.youtube.com/watch?v=zN1pp...
Trailblazer battery disconnect side effects:
https://www.youtube.com/watch?v=NsIW3...
TLDW alternator noisy, swapped back to stock for now