Check these two fuses to make sure they are not blown and have a good connection. If the fuses are good, then pull the starter relay with the key on and jump pins 30 and 87 on the fuse block, if it cranks then you are looking at a problem between the fuse block, ignition and starter relay control side. If it doesn't crank, check for voltage on pin 30 of the starter relay, if it has power then you're looking at a problem between the starter relay output and the starter solenoid. If there is no power on pin 30, you have a problem between the fuse and starter relay.
If the truck cranks when you jump the pins on the relay, check for voltage on pin 86 when cranking. If no voltage, you have a problem between the starter relay and ignition switch (its possible the switch is bad) If you get voltage, check for continuity to ground on pin 85, if there is none, chock the wheels and check for continuity while someone slowly moves the shift lever from park to drive and back. If you do not get continuity during the procedure, you're looking at a problem with the neutral safety switch or its ground.