I have a 85 cutlass with a 350 engine i need to know what belt i need it sqeeks very lound dnt seem to have the answer for it. It stops when the cluth fans kick but when it first start

I`m guessing that you are trying to find out which belt is making the noise.first you need to push on each belt to see if the belts tight and not to loose,at the same time check the sides of the belts for a glaze or shiny sides as well as cracks in the belt .any belt that is to loose may just need to be tightened, any belt that is glazed or cracked needs to be replaced.if the condition of the belt is good then it probably just needs to be tightened.a trick to find which belt that maybe just loose enough is to take a wax candle or a bar of soap and with the engine running(being very careful around moving components) take and apply the wax to each side of the belt one belt at a time, when the noise stops that is the belt that needs attention either by replacement or tighting