72 Chevrolet C10 Electrical issue

[Ejlfson]

I have a 72 Chevy C10 that I am having starting issues with. Initially wouldn't crank when key was turned. Determined it was a bad starter and replaced with AC Delco starter. Started fine at first and then began clicking when key turned, but wouldn't crank. Replaced that starter with a low torque from Summit Racing. Now having same issues. It will start on first turn sometimes, and then on others will click once, twice, maybe three times before turning over and starting. We replaced ignition cylinder and switch to rule those out. We checked the battery and + and - battery cables/connections on battery/starter and they look solid. Battery is completely charged and load tested and is good.
I'm at a loss for what I should do next. Any suggestions would be appreciated.
Thanks.