Thanks for choosing Just Answer! When you say it clicks is it clicking at the solenoid itself or at the starter? If it is at the starter, take a hammer or an object and hit the starter while someone tries to start the truck (Make sure the parking brake is on and the gear selector is in the park position / neutral if a manual trans. this is to make sure you dont get ran over on accident.) If it starts then you need a new starter, if it is clicking at the solenoid you will need to take a screwdriver and jump the solenoid, to do this turn the key to run, then touch each of the large posts with the screwdriver, if it turns over then you need a new solenoid. If none of that works let me know, and i will assist you to solve your issue. Any questions let me know.
They call it the starter relay on this truck although it is also known as a starter solenoid (same thing just different name) I have attached a picture of where it is located. I would almost bet you have a bad starter solenoid (relay) try the screwdriver trick to jump it, I bet it will start.