I have a 1979 chevy truck and it won't start it has a new battery and good starter but it only clicks sometimes when I try to start it?

This link may help:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-3.html#post235560

Clean starter motor connections and apply dielectric grease. If problem persists, focus on the solenoid.