Elec woes, crank, no start after running then parked.

I had same issue that required a tow off highway 401. It was an "oh ****" moment to say the least doing 70 mph and all of a sudden no power and 4 quick lane changes lol. I eventually ended up rewiring my entire dash harness and also discovering several distributor issues.
Good luck, follow a lot of the tests here, and another thread I started back years ago. I'll try to find it for you.
**edit**
Initially way back when issues started my dash harness LOOKED great, but its 50+ years old and the insulation was cracking etc.

my5thmopar said

I had a very similar no spark issue the other day after a short drive. This is the 3rd time. I tested everything in the shop and all ok. When the no spark issue happened again, I was going to catch a ride home for parts. I didn’t have anything to hot-wire it with. I reached under the dash and wiggled the ignition switch and it started. I haven't pulled it out for testing.

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