When it rains pours...

I noticed my Charger wasn't charging (via the ammeter). It went from a heavy discharge at idle to breaking even (dead center) when I revved it. I checked the voltage at the battery (running) with 12.2V @ idle and only 12.5V when I revved it. This alternator used to put out 14.5V all day long.

Alternator is a 100 amp Tuff Stuff unit (8 years old at this point) and car has 40 amp electric fans. I inspected the wiring and connections and all looked good. Wiring is reproduction installed around 12 years ago.

I went ahead full fielded the alternator (to eliminate the regulator).
- voltage at the blue field wire tested at 11.9V when I pulled it (battery voltage was 12.2V)
- I plugged this back in and pulled the green field wire
- I connected a remote starter to the (green wire) field terminal and ground

The alternator definitely kicked on and slowly climbed to 12.8V very very slowly. I revved the motor (while full fielded) and it slowly climbed to 13.8V (maybe took 30 seconds).

This seems very slow compared to what I have seen when I full-fielded alternators where they would jump to 15+ volts immediately.

Can I pretty much assume this alternator is dying? Anything else to check since I eliminated the VR?