While chasing down a minor squeak (turned out to be the alternator), I noticed my serpentine belt was missing a few ribs, so I bought a new one and installed it.

Immediately had significantly more squeaking. Sounded "almost" like a slipping belt, but nowhere near as loud.

I tried everything to determine which accessory was making the noise, but couldn't pinpoint it.

After reading this thread:

https://blazerforum.com/forum/2nd-ge...nt-stop-58124/

I took the new belt off and looked at the ribs. One of the edge ribs was barely larger than the other; the belt was cut slightly off center and causing one edge to rub against the side of the pulley.

I exchanged the belt for one that looked like it was centered - problem solved.