I have a '93 D250. A couple of times rolling along at 55 the voltage gauge has dropped and it kicks out of OD.

I've been searching all over the threads and found a few associated things my truck does sometimes:

-occasionally I turn on the A/C but the compressor doesn't kick on, if I try it a minute later it usually works

-sometimes the CD player hiccups (could be losing power for an instant)

I had my alternator checked its running at 13.2. The battery checked out okay too.

My guess is the crank sensor. Thoughts?

 

could be the crank sensor, but also check to see if you have a good body ground.

 

I found some corrosion on the terminals and the water in the battery was kind of low.

It's been behaving so far.

 

the alternator shouldnt be putting out less than 13.6 volts with the trck running. turn it on and put some loads on i, head lights on, radio on, and ac/heat on full. see what the voltage is at after that. then turn the truck off and check the voltage on the batter with the meter. shouldnt be under 12.6 but it may climb a little after you shut it off