This works for 12 volt systems:http://www.watsons-streetworks.com/docs/a-current-topic.pdf The normal Bosch relay should work on 6 volts too,your 60 year old OEM relay may be on it's last legs so byp*** it, and give this diagram a try if it doesn't work then you can keep it in place and go 12 volts.Here is what is involved in converting:http://www.ebay.com/gds/6-to-12-Volt-Conversion-1955-Ford-/10000000001571127/g.html