I've got 1/2 dozen factory ICM's for GM HEI and have never had to use one. Back when I was working on airboats with Cadillac motors on them I never saw a factory ICM go bad. If they'll take direct salt spray they've got to be tough.Not OBS but similar issue. I bought the GM style HEI distributor for my 75 ford with an FE block. I like the HEI and it simplifies parts for me. Driving it one day and it shut off, towed it home and they had used a soft roll pin for the gear. Installed a proper hardened steel roll pin and was back in business. Then my son was driving it and it shut off again, towed home and replaced the ICM with a high quality one and it has been good since. Cheap is cheap.