Easy way to check to see if Alternator is good

Ok, love my 95 PS, but went to get in it yesterday morning, turned key and got click, click, click. It has two brand new batteries and a brand new starter and brand new starter solenoid. My first thought is alternator. I know with a single battery vehicle, you can jump it off, and remove the battery cable and if alternator it will die. But is there a way to check on diesels? Considering it sat for about 2 years, I am expecting little issues to pop up, but it is a bit frustration

Sounds like you have a parasitic drain on the batteries. Start by charging the batteries fully, disconnect the negative terminals on both batteries before starting the charge. After charging, reconnect Neg. wires, with a small wrench put it on the backside of the alternator, if it sticks or if it feels like it want's too, then it has blown diodes in it, need new. Alternators are not made to charge dead batteries. If the alt. is OK, disconnect the Neg wires again, then connect a test light from one Neg. terminal to the frame or engine, if the light lights, then you have a parasitic draw, start pulling fuses until the light goes out, that will be the circuit that has the draw.

After the batteries have been disconnected, it will set a code, KAM (keep Alive Memory)

Common draw causes:
Doors not closed tight.
Key left on.
Dome light left on.
Radio left on.

Thanks. Will do that tomorrow after church, working today. I know there may be little things pop up, just did not expect it so soon.

Check voltage, start vehicle, check voltage while running. you should get 1-2 volts over the battery voltage. Sometimes you get a little more, that's OK as long as it never hits 15 volts, should never get above 14.7 really.
Not enough DC voltage can be a million problems. Too much DC voltage means bad wiring (possibly to field) or regulator.

You can also test for AC voltage, more than a tiny amount of mV AC (yes, AC!) indicates a failing/partially failed diode.

Alternator is good, will have to figure out why radio is draining, until I have time to do that, simple solution is to leave radio off

on mine with an aftermarket head unit, it was miss wired that the factory amp was always on
drained the batterys in about 2 days if not ran