Will the starter motor run without engaging the drive gear? Just use a big screwdriver or a pry bar to depress the switch at the starter housing without pushing the pedal to engage the drive gear in the flywheel. If the starter runs that way, check to be sure the engine isn't locked up by putting the truck in high gear and rolling it forward. The engine should turn.

Did you bench test the replacement starter by connecting jumper cables to it and operating the linkage? "New" doesn't always mean "good". In this kind of situation simply throwing a wheelbarrow full of new parts at the job doesn't mean you have diagnosed the cause of the problem.

Would you allow a doctor to start doing major surgery on your body without a good diagnosis of what's making you sick in the first place? No difference!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!