Most alternator problems involve worn brushes and/or the voltage regulator.

Having rebuilt numerous alternators, over the years, I've come to a conclusion. From an engineering design and maintenance point of view, alternators in American cars are better than most Japanese imports. The key difference is the location of the slip rings. On most American alternators, the slip rings are located behind the rear bearing. This allows the voltage regulator/brush holder assembly to be changed in minutes, even on American cars with an internal regulator. On many Japanese alternators, it's very difficult to replace brushes and the voltage regulator. The whole alternator needs to be torn down, brushes need to be unsoldered/resoldered, and the voltage regulator replaced. Instead of a 5-minute job, on the car, it ends up taking many hours to remove and service the alternator.

Keep in mind that you can rebuild an alternator, including bearings, brushes, and voltage regulator, for 1/10th (or less) the cost a remanufactured one. Many "remanufactured alternators" don't even come with new bearings.