my dad's friend, has '96 Dodge 2500, His alternator gauge showed it wasn't charging, took it to O'reilly auto, and they tested the Alternator, tested good 3 times. Check all the connections, and put a new crank sensor on it, but it still shows the Alt. not charging.?

check the wiring, especially ground wires

He's checked everything you could possibly think of. He is is thinking it might be his PCM.