Our town had the largest gm cast iron foundry in the US. Now it's shut down has not poured any cast in probably 8 years. It was set to be torn down. I think cast iron will never return to production of equipment we loved of the past.Well Chris if you find anything that's any good please post an update. Everything I've found has been made in China from Chinese steel which has turned out to be soft and bendy. The last set I put on I heated the cutting edge with a torch until it was red then dipped in water. I'll find out at the end of the mowing season whether it had any benefit or not. I wish somebody would start up a mower blade company in the US and make stuff from US steel like they did in the days when Cub Cadets, John Deere and Sears Suburbans came with cast iron transmissions.