The "one year" noted above that Chevrolet featured a two groove pulley BEHIND the balancer was 1957. I have one I pulled off of a 1957 Chevrolet car 235 at a wrecking yard a few years back. At the time I thought it was luck finding it, now I know it was luck finding it. It is amazing to think that they used a two pulley behind the balancer for only one year!
Joe
