I have tried replacing the belt twice.
That stop it for about 3 days then it comes back ..Soap or belt dressing quitens it for about an hour. I have replace the tensioner pulley the main pulley and like i said the belt. Does anyone else have this problem.?

It may be the rear altenator bearing, try spaying the bearing in the rear of the alt with wd40 while the vehicle is running. If the noise quiets do the same using SUPERLUBE. Do this carefully and dont use to much, also the bearing will look rusty!! It worked on my Caprice.

thanks dude I will try it tommorow.!!!
Ill let you know!!!

If the dressing doesn't do the job, you may need a new tensioner.