The last time I replaced the intake gaskets on my '92, I ended up with a kind of squeel. It did not sound like a belt.
Well, I remembered that I had lost one of the two mounting bolts for the alternator and thought that I could get along without one of them for a day or two. Really, one bolt, I figured, would keep the thing from falling off for a while anyway. Using only one bolt was allowing the alternator to vibrate and make a noise resembling a banshee! The alternator was NOT loose however! I would imagine that a mis-tightened bolt might make the same noise. You might want to check all bolts. Maybe you'll get lucky.
2001 SSEi- black; stock 92K
1995 Vette; Competition Yellow; stock; 38K