Your tractors are correct. There is some disinformation being posted here. Ron Cook, Salix, IA On 7/26/2016 8:27 AM, Eileen Brazil wrote: > Interesting ... my 1948 D has two 6 volt in series, but my 1956 420 and 1955 40C have single 6 volts. There's no room for two batteries and the 6 volt system is original according to the shop manuals. >