It wound up being the regulators. I had rebuilt the alternators a couple years ago and used aftermarket regulators. I replaced them this time with OEM Motorcraft ones from High Output Alternator, 200-250-300-350 Amp Alternators, high output alternators, Delco Remy,Ford Truck Alternators
The way I tested was unplugging the alternators so that only one was functional to see if it was one or the other. Since they both fluctuated, I knew is was a truck wiring problem OR BOTH alternators had an issue.
The only reason the alternator would put out more voltage if the alternator was in good condition is if the sense wire was picking up a low voltage and the alternator was trying to compensate. To eliminate the truck wiring as the culprit, I wired a jumper from the sense wire to the battery positive. This way I know the alternator is seeing battery voltage and not a drop from where ever it normally picks up the signal.
It still had the high voltage jumps, so I determined it must be the alternators. Ordered up the regulators, swapped em out, and all has been good since.