Many dial back lights are confused by Msd type of ignitions. Ferret made the best timing lights but they went out of business. They where sold as several different brands Including Msd. Maybe Msd bought them out?

I don't own a dial back. The non dial back chrome sears craftsman/penske lights have been reliable for me. I also have a D cell light that works and has less wires to get cut or melted.