No spark 1973 360

It might be as simple as loose/ corroded connectors. Pull them apart and inspect. I BELIEVE that the cylindrical connector terminals such as the ECU, the VR on 70/ later cars, and the dist. pickup connector is about the same dia. as a flat trailer connector.

You can I believe clean them with a .177 rifle bore brush. That is correct, .177, which is a rifle caliber same size as BB/ pellets.

As someone mentioned, the ECU MUST be grounded. Remove and inspect clean/ scrape around the firewall and ECU bolt holes, and remake using toothed "star" lock washers.

The dist pickup connector is especially vulnerable as it has no real current going through it. After cleaning, "work" the connectors in/ out several times to further scrub the terminals. It does not hurt, if you have it, to use some sort of electrical de-ox or other terminal protectant. First time I saw that was on a 79 Ford I had, as well as the Trucklite sealed tail lamp connectors.