['63GENIII]

Miss alignment or possibly one or more of the accessories are dragging causing too much strain on the belt? If you look from the side of the belt(s), they should be darned near in line with each other. If one pulley is slightly off, you can have some problems. Id also try watching (make sure to stay out of the line of the belt) all of the pulleys while the engine is running to see / hear if you can pinpoint the problem. The belts on my 396 required a little maintenance more than I liked. I went with a factory serpentine set up and never looked back. No power steering belt squeal since.