Just go ahead and replace the alternator?
 

Car runs just fine ('83 SC), but today I noticed that my voltmeter was indicating a charge of no more than 12.5 volts. Confirmed that with a multimeter at the battery, at 2,000 rpm--12.5 volts. "Resting" voltage of the battery, engine off, is about 11.8 volts.

Battery is a six-month-old Optima, and whenever I park the car for more than a few days, I turn off a master switch. Fan belt was replaced about six months ago as well and seems to be tight--no slippage, I can turn the crank by turning the fan.

The alternator was rebuilt/rebrushed by a local alternator shop about 14,000 miles ago, but I'm pretty sure it's the original alternator.

Since these are the Paris-Rhone alternators with integral regulators, should I just go ahead and replace the whole thing?

Stephan,

Since the voltage does not increase as the engine revs, agree it's the alternator.

You could remove the regulator/brush assembly and check the brushes first. If they are worn down, there will be no field current and no alternator output current or voltage.

Thanks, Ned. I'm pretty confident the brushes are good, since they're only a few years and limited miles old. And I see that Pelican has an apparently new line of new (not rebult) high-output Bosch replacement alternators, and I'm always a sucker for yet more gold-plating...