Alternator question

The thing is, if your battery is healthy you should be able to drive it a LONG time with just the battery. Night of course will be less, you won't make it 2hrs on headlights. But with no lights you should be able to drive most of a day if you don't stop and restart the engine very much

So far as fixing it, what do you have? You still have the older (69/ earlier) single field connection, or the newer (70/ later) so called "dual field" (two field connections?)

Might just be bad brushes. First thing I'd do is rig power to the field and see if it charges.