Would a bad alternator cause headlight flicker?

On my 1968 Barracuda, there are a couple issues that lead me to believe my alternator is on its way out... Primarily, there is often a metalling whirring/squealing noise when the engine is running that sounds an awful lot like bad alternator bearings.
Secondly, when my headlights are on, they flicker (in terms of dimness). Are these two separate issues, or do I need to pony up and buy a new alternator or rebuild it? Also, could the headlight issue be a regulator or something else?