Dead in the water?

I bought an '87 new. (Standard model, Z24) 370,000 miles on her, it could be anything BUT:

A few times turning the key produced nothing, I thought it was strange and hoped I had actually depressed the clutch pedal, tried again making sure to push the clutch down and she fired right off.

Then one day nothing. (To clarify: all dash lights come on with turning the key, a slight click with turning the key to start and then back off, but no attempt to fire or anything else)

So I assume / hope it's the (original) switch mounted under the dash that the clutch pedal hits, preventing you from trying to turn it over when you're in gear. I replace the same switch for the brake pedal at the same time. The original switches are NOT interchangeable. The aftermarket brake switch (called stop light switch) does NOT plug into the terminal for the clutch switch. No aftermarket clutch switch is available.

The dealer clutch switch is visibly WRONG. The terminals won't mate. The dealer stop light switch fits BOTH terminals, but doesn't help. (Doesn't change anything at all.)

Obviously I want to eliminate all possibility that the problem is merely this switch before I go on a wild goose chase, and my dealer couldn't care less, saying it's got to be something else. So why would Nissan make 2 different parts, with 2 different prices, if 1 would serve the function of both? Seems to me I haven't yet eliminated this switch as being the source of my problem.

What can I do?

Got 'er going. Found the thread re: '94, and had myself all lined out w/ spade to spade connector, jumper wires, etc. (All of which now LIVE in my glovebox, BTW)
Figured I'd leave each in place as I went through the whole works.

Turned out to be the first really bad piece of engineering I've found in this vehicle so far:

a small, round, plastic disk. It was on my driver side floorboard the first time it wouldn't start, last April. I laughed, thinking there's no way this could be it - right?

There are 2 CSS (clutch safety switches) One at the top of the pedal motion, and one all the way at the bottom, which makes the top (and more obvious) one completely unecessary and unhelpful if you ask me. The switch at the bottom lines up perfectly with a HOLE in the pedal?!? The plastic piece was glued onto smooth, painted metal, with no texture to anything, and stayed in place for 22 years + through all kinds of weather, high humidity, etc. Just trying to leave me stranded someplace the whole time!

So I was stupid enough to actually try to glue it back on. Thank God that didn't work, so I did some very crude sheet metal work, not much more than a tinfoil hat really. Works just fine. If it ever falls off, (doubt it) I'll just slide it back in place ...

Something to check for anyway, before you go spending $$ on ignition switches etc.

And the visibly wrong CSS may well go at the bottom of the pedal stroke. The brake switch (stop lamp switch) works in the top clutch position as well as the brake, although my original top clutch switch still works just fine.