64 Ranchero no crank

I have a 64 ranchero that will not crank period, the battery is fully charged and the starter relay has already been replaced. the starter will turn over when battery power is jumped directly to the "s" terminal. When the key is turned to the start position, there isnt any power present at the "s" terminal. Any ideas/input?

That test tells you a lot: the relay and the starter are fine, and the problem is the wire that is supposed to bring power to the relay's S terminal when you turn the key. That wire comes from the start terminal on the ignition switch, and on an automatic it passes through the neutral safety switch on the way.

Work back from the relay with a test light, key held in START:

1. Is the trans an automatic? Try starting it in neutral as well as park, and wiggle the shifter while holding the key. If it cranks in one and not the other, the neutral safety switch is out of adjustment or bad.
2. Check for power at the start terminal on the back of the ignition switch. If it is hot there but not at the relay, the wire between them (or the neutral switch) is open.
3. If there is no power out of the switch's start terminal, check that the switch has power coming in on its battery terminal. Power in and nothing out in START means a worn ignition switch, which is common on these cars.

Dana