[tomj76]

I've replaced the alternator several times, but always with one from a US chain store supplier. The last time I replaced it was unnecessary because I misdiagnosed the problem.

I have also purchase some other items through the mail, from various suppliers such as Amazon, RockAuto, AutoZone, and Advance Auto Parts, and often found those items don't work "as advertised". Usually the are OK, but not always.

Most aftermarket alternators are advertised as re-manufactured or rebuilt. The usually paint them black with a very fragile paint when this is the case.

If your unit seems to have the wrong parts (e.g. bearings that don't fit correctly), there's a good chance it was rebuilt.

The Ford Windstar uses a alternator/generator design, where the regulator manages the output voltage by adjusting the current in the field winding to increase or reduce the alternator output with load conditions. The main failure points are bearings, brushes, and diode pack. There are rebuild kits available for the bearings and brushes.