[jeffcoslacker]

How sure are you of the battery's condition? If the battery has lost water from all the charge/discharge cycles it's been through, that can cause the regulator to shut off charging intermittantly...

The primary wire that charges the battery from the alt is easy to spot...it's a fatty wire running back to the positve side, can't remember if it goes directly to the battery on those or to the power distribution box there but it's real easy to spot and trace...make sure it's solid all the way to the alternator.

Check charging output at the charging terminal on the back of the alternator...should see 14v or so there at idle...if you see less at the battery then that wire may be bad, if you see the voltage cutting back at the charge terminal then the regulator is commanding the cutback, you have to find out why. Check the wiring for the regulator carefully for soft spots or burns.

Some older ones would fry the wire from the regulator to the ECM, and the ECM would get an incorrect or intermittant voltage reading and signal the regulator to cut back on output...

A shorted battery will make the reg cut back also...but shorted batteries usually will fail to start and reject a jump/charge from time to time and then suddenly start working fine...