I am working on a 1940 caddilac limo with my dad and I have two diagrams one is poss ground and the other is neg ground for the wiring.
before hooking the guages up I would like to know what is right.
Brad

Would it be possible for you to "scan" and E mail to me a wiring diagram that you have, that says 1940 Cadillacs have a "negative" ground electrical system ? This would be most interesting, as most pre-war GM cars had a POSITIVE ground system.