That GM HEI system was one of the best in its time. Although things would go wrong , the module or the coil. I remember putting a coil or a module in them on the side of the road a couple of times. This was back when parts houses had parts in stock...another thing was the clip on the hot wire would break,and every once in a while the engine would shut down, then ya pop the hood and reattach the wire and off ya go...