2006 f350 not charging

I have a 2006 f350 6.0 and I’ve change the batteries
out, tried 4 different alternators that I know where
good, replaced glow plug control module cause it
was staying on and I though that was my issue and
have tried a jumper wire from the alternator to the
batter to make sure the stock wire was just weak
and I still can not find my issue I’m only getting
11.1-12.4 volts out of the alternator. My gauge
cluster did start shutting off previous to this issue
but hasn’t since so I didn’t know if there was
something that links those two together. I’m at a
loss here and currently out of a work truck so if
anybody has any suggestions I’m all ears. I did take
it to a mechanic and the glow plug issue is what
they came up with.