I have a 94 gmc k1500 5.7 and it won't stop squeaking. I've replaced the tensioner and the idler pulley and the alternator and the power steering pump. And the belt. Because the tensioner seized. Every time I've taken the belt off to change something the squeak disappears for about a day or two but then comes back. Also it doesn't squeak after it has been driven for a while. But once it cools back off it comes back.....

 

I had a simular issue on an old Chevy Scotsdale I had. Try spraying a little silicone lub on anything that turns...pulleys, etc. I drove that truck for 15 years and sometimes in older trucks, they develop a personality that just has to be accepted.

 

I would clean all of the pulleys to ensure there's no grease/debris on there that may be continually causing the belt to slip.

 

I took some simple green to it all and the first time i started it, there seemed to be less squeak. but there still is some. my dad took some wd40 a few weeks ago and sprayed the back of the power steering pump pulley and it stopped squeaking...so initially we believed that was the problem. i guess i just need to keep cleaning until theres nothing left... is it possible for the fan clutch to squeak? ive messed with one before on my s10 a while back but it was because it just gave up all together..