Good afternoon, I have a 1988 F150 i6 4.9l 2WD. I am not able to turn on this truck with the key, I have had to start it via solenoid. Then after a while that even stopped because the starter seemed to seize up and wouldn't turn anymore. So I replaced the starter, the fender mounted solenoid and the neutral safety switch(it's attached to the clutch pedal) but still nothing. When I turn the key everything turns on as it should but the starter does not engage. Can anyone offer any mechanical advice as to what to do next? Thanks in advance.