I need help!! After narrowing down an electrical issue to what appears to be the ignition switch in our 55 F100 (still original 6V system), I went online and ordered an new one.

It seems all that is available is a universal switch that can be used for 53-56. Since 56 is 12V there is to be a 4th post on the new switch that the 55 switch does not have.

Does anyone know how to install this new switch on a push button 55 6v. The 3 posts on the 6V switch are marked GA, AM and COL. The 4 posts on the new switch are marked ACC, BAT, IGN and STR is the post in the middle. What goes to what??

I tried to attach pictures and the instructions I got but it won't let me attach files.
Thanks,
Deb