Tensioners and pulleys

I've noticed that one of my pulleys has a squeal after the truck is driven. I can't tell which one it is, and they all look old, so I decided to replace them all. It's a simple remove & replace procedure. Here are the parts I used: Gates 38587 fan/alternator tensioner ($120) - remove with 15mm socket Gates 36286 fan/alternator idler pulley ($62) - remove with 14mm socket Gates 38610 A/C tensioner ($119) - remove with 8mm Allen head socket Gates 36223 A/C idler pulley ($39) - remove with 15mm socket