Wire harness differnece. Clutch dissengage/nss switch help needed

If the new harness does not have those, does the starter interlock circuit even have continuity while cranking?

If you wanted to, you could create a new interlock circuit from the ignition switch to the starter solenoid.

No need for a battery - do continuity testing instead. The diagram I'm using as frame of reference:

http://www.veryuseful.com/mustang/tech/engine/images/Mustang-86-Mustang-ECC-EFI.gif

I guess what I would do is simply ensure the white/pink wire has continuity to the red/lt blue wire. As you know, set your meter to the low Ohms scale and connect a lead to each wire. Be sure both ends of the harness are disconnected (i.e. be sure the red/lt blue wire is not connected to the solenoid, and it'd be nice if the ignition switch was disconnected). The meter should read under 5 ohms (it will probably read a fraction of an Ohm) if there is continuity. If there is continuity, the clutch switch is jumped or it's missing. If there's no continuity, you'll have to trace the harness to find where the circuit opens (likely at a pigtail for the clutch switch). If you find the switch or what you think is the switch, a blade fuse should fit in the connector to jump it for testing (as soon as the fuse is installed, the circuit will show continuity). Note that if the '86 has cruise and is like the aero cars, there's a second switch on the clutch pedal (for the CC). This is not pertinent to the interlock circuit or testing.

The testing should take but a minute and you'll know if the interlock circuit is intact or not. If it's not, you can trace the actual wire to find the issue or just run a new wire.

Post up what didn't make sense. I'm not that articulate.