[billthompson]

sounds like a bad switch...how old is it? sounds like youve done a lot of electrical additions. do you have an hei or points distrib? if its hei, you could run a temperary wire from the battery to the hot side of the hei. if its got a coil you may need a resister in the wire so you dont burn the points. if it runs ‘hotwired’ then you know the problem in your switch circuit. not a lot to the stock wiring on our trucks but your mods might need to be looked at.