More trivia here:
@904Bronco said "I believe that most Ford applications had a Manual Trans safety switch that was on the clutch pedal."
There is no such thing as a Manual Trans safety switch in a Ford with EEC4. So that's correct.
" I don't believe there is a manual trans with a neutral safety switch in it like the back lights switch."
The Ford nomenclature for the thing on a manual transmission to inform the status of neutral is called the NSS, or Neutral Sensing Switch. The engineers in the Ford controls group think that they are quite clever. They KNEW that everyone called the NSS the neutral safety switch. But they call the circuit the NDS, or "Neutral Drive Switch." HOWEVER, the Sequential Multi-port EEC4 system is looking for the transmission status. So the T5 Manual transmission in the 1986-93 Mustang 5.0 is equipped with an NSS (sensing) that works in series with the CSS (Clutch Safety Switch) to inform the ECU when the car is in neutral / disengaged from the drivetrain. It does in fact look like a back up light switch on the transmission. (Don't get me started on the Brake On - Off or "BOO" switch.) The wiring for the starter circuit is isolated from the NDS circuit. There's two switches on the clutch pedal switch.
The manual transmission with the ZF in the fuel injected F150 does NOT have an NSS.
5.0 EFI systems running the RJM/Ron Francis/TDZ harness defeat the NDS circuit. Explorer EDIS doesn't care, because they were all Autos.