1966 Chevrolet Malibu Just Replaced Battery Starter Alternator Year Old

Yup. That will have a mechanical voltage regulator that uses relays. They kick in and out at various voltages. Typically you might see an occasional blink to a higher or lower brightness if you're really paying attention, but sometimes they cycle rapidly between two states when the battery voltage is right on the borderline between two voltage set points. It was also common for the relay contacts to become pitted or arced. They could stick together or the arcing could cause very rapid flickering of the lights.

Start by removing the cover from the regulator and using a small flat file or piece of sandpaper to clean the contacts. Some people have installed electronic voltage regulators that have infinitely variable voltage settings with no flickering. One way to do that is to install the next generation of GM generator with the internal voltage regulator. That was one of the best systems they ever produced. They used that design through 1986 models. The new design for 1987 that they're still using is a disaster and should be avoided at all cost.

You can also wire in a 1970 - 89 Chrysler electronic regulator. They will even run their newer Chrysler alternators. They're very reliable and inexpensive. If you get one from a salvage yard, snip the two-wire connector off and take it too.