1974 Duster total electrical failure, followed by quick recovery.

If the wires from the battery and alternator feeds go through a grommet in the firewall, then your car has one of the optional heavy duty wiring arrangements. Some of those have two fusible links. Cars with rear defrost grids had this arrangement.

With the standard wiring the bulkhead connector is a somewhat weak link.
Removing and cleaning and even repairing isn't that hard once you'r doing it.
Discussion about removing the connector engine side. question on the main harness plug on firewall

One of a couple discussions on cleaning here:
Cleaning bulkhead connectors