speedo cable Question

[shiifty_dart]

I was wondering if there were any darts made with a 5/8 by 18 nut on the back of the speedo and if so what years and if not does anyone know of an electronic speed sensor that will work with my 727 and electronic speedo
thanks in advance for all the help

 

[Longgone]

I think they`re all pre `68.