please list codes. are there any modifications or tuners on the truck?
the crank sensor is self aligning. basically the reluctor wheel has a missing tooth the the ecm uses as the starting point. if the sensor does not send the signal or the ecm doesn't get it the engine wont start.
make sure the sensor is fully seated and no debris between the sensor. check if it will start
if it still wont start then check for any bad wires or shorts with an ohm meter