You said belts. How many belts and which one is squealing? You didn't say if any of the pulleys squealed at start up? Do any of the pulleys make too little contact with the belt? 1/4 of the circumference or less? Do any of the pulleys need to be made larger to improve the contact area and reduce the speed of the accessory?
A picture of the setup would go a long way.


'67 GMC 3/4 292 4spd