Voltage problems, cutting out when hot

A '72 has two big differences from a 60's type scheme shown above.
ECU ?
Some '72 cars may have had a Chrysler ECU, but I'm assuming here that the ECU wiring was added. A factory ECU from the time would have two resistors and 5 wires.

View attachment 1715370660

The car in question is a 1974 so it came factory with the 5 pin ECU.

What do you have from the key switch? Functional path is power to ignition switch---out of the switch on "ign1" (ignition run)---through the bulkhead connector,---and to one side of the ballast. If you can't find that wire, disconnect at least 3 of the ballast wires and look for the only one which has power. Note that, hook everything back up, and measure that point---key in run--engine stopped
Thank you for the idea, I’ll check at the switch as soon as I can get back out there.
First and foremost I’ll be doing away with the fans in the circuit all together for testing then I’ll be switching fan power to the alt side of the charging system.
I have seen batteries that cause a car to stall while cornering hard. Loose plates.
Perhaps not the case here,but a battery swap is pretty easy.
I replaced the battery with a new battery (2 months old) and had a local shop load test the battery in the car, it tested good.
Again, I appreciate all of the input.