Ford 302 no start no crank

1979 Ford ranchero 302.
No noise or power when the key is turned. I have strong headlights no dimming but no radio.
Sometimes it will crank right up but most of the time just no life.
The battery is good the solenoid and starter are good.

No

Clean the battery terminals, starter connections, ignition switch connections and grounds.

A good thing to replace on an old vehicle is the positive battery cable that runs to the starter. Sometimes the whole darn thing is completely covered in corrosion.

If you turn the key and get stone-dead silence, it is often the neutral safety switch. It ensures that the car only starts in Park and not in Reverse or Drive. The switch is near the gear shift so it could be under the dash atop the steering column or (for floor shift) beside the transmission beneath the floor shift.

It's a fairly common thing to break on an old car and not too difficult or expensive to put in a new one. As far as I know, when it goes, it goes. It doesn't start sometime and not start other times.

As a starter gets older it takes more amps to crank it until eventually a car battery isn't enough. You can bang on the starter with a rubber mallet or 2 x 4 and then try cranking it. It usually works. Some guys have driven trucks like that for years.

Huggy's answer is the FIRST thing you should do - make sure electrical connections are clean, shiney and tight. It doesn't cost anything and often the culprit - this includes both ends of the battery terminal cables and starter solenoid connections. When it doesn't start try tapping on the solenoid/relay with the back of a screw driver and try again - if it goes- likely defective relay (cheap to replace) to be certain try putting the other end of the screw driver across the two lugs of the solenoid to see if the starter will spin when it fails. If so pointing at a bad solenoid again.

Time to pin test the ignition switch with a test light or volt meter to see if there's power to the starter solenoid when the key is held in the start position. If it's an automatic that circuit runs through the range switch/neutral safety switch. If it's a stick shift test the clutch pedal safety switch to make sure it has power in and out when the pedal is held to the floor.

If it is a sometimes problem try tapping on the starter solenoid when it doesn't make any noise and does nothing. Nine times out of ten it is the coil in the solenoid worn out and binding in the solenoid and tapping lets it jump loose and pull the contacts closed. Replace the starter solenoid.