I'm having a chirping noise around the alternator area on my Chevy Silverado 2007 (4.3 L V6). I changed the serpentine belt and that helped some( no more squeaking), when the belt was off i spun all the pulleys by hand the alternator pulley has a slight squeak when turned by hand. Now the belt squeak is gone, there is still a chirping.. I spray the center of the alternator pulley with Wd-40 after i start up and it goes a way right away for a short time. It seems like when i get going for a while it goes away for a while. I want to say its the alternator. It seems obvious where the noise is comming from, but still wondering if i should change the alternator, wait.. or try to change the pulley or bearing? Does this seem like something would be bad to put off for a little while? Truck runs fine, No other issues other than the noise. I have about 60,000 miles on this truck, its the original alternator.