Replaced starter, still doesn't start at random times, all electrical working, no sounds just doesn't start, after sitting awhile starts right up

Maybe starter solenoid frozen up next time try to hit the solenoid with blunt end of screwdriver then try and crank it again.

If the truck was doing the same thing prior to replacing the starter you are using the replace and hope method, which gets expensive. I suspect you have a bad solenoid. There is a method to bypass the solenoid on vehicles with a distributor or electronic ignition. They are different. Check the internet for instructions.