I'm new to Olivers and to this forum. I just bought a 1964 550 with a leaking water pump. The only one I see is for a sheet metal pulley. Mine has a cast iron pulley. The listing for the sheet metal one says it will not work in place of the cast pulley. What to do? My s/n is 140719. I did find one with the same casting number as mine but the picture shows no pulley at all and I see no way to take my old pulley off of the pump.