Ignore the first post then, i just saw this one afterwards which you clarified it being the serpentine belt. In which case, you need to find the alternator. Found it? good! now check the bracket holding the alternator in place, there should be a bolt on there that holds it tightly to some sort of track allowing you to change the angle the alternator is sitting at. That one is the adjustment bolt that allows you to tighten or loosen the serpentine belt. On those years, GM used the alternator to bind the belt to save money on design. So just loosen the bolts on the alternator, bring it up to loosen the belt (you might need a prybar to help you move it), BUT BEFORE YOU TAKE THE BELT OFF, make a diagram of the belt routing, cause once its off if you don't have oneon hand, putting a new belt back in can be pretty tricky since there are many curves it needs to take and can seem to be in the right place on either side of the pulleys, but it will end up being too tight of too loose.
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Ignore the first post then, i just saw this one afterwards which you clarified it being the serpentine belt. In which case, you need to find the alternator. Found it? good! now check the bracket holding the alternator in place, there should be a bolt on there that holds it tightly to some sort of track allowing you to change the angle the alternator is sitting at. That one is the adjustment bolt that allows you to tighten or loosen the serpentine belt. On those years, GM used the alternator to bind the belt to save money on design. So just loosen the bolts on the alternator, bring it up to loosen the belt (you might need a prybar to help you move it), BUT BEFORE YOU TAKE THE BELT OFF, make a diagram of the belt routing, cause once its off if you don't have oneon hand, putting a new belt back in can be pretty tricky since there are many curves it needs to take and can seem to be in the right place on either side of the pulleys, but it will end up being too tight of too loose.