The Vans have a slightly better track record. They are a detuned version of the same engine. They also have a better locale for the FICM that lengthens its life.
Unless that Ambulance company is on top of the flushing of the Ford Gold (every 40-50K miles) and continually checking the nitrites, they could swap them all over to the Fleetrite ELC (or Rotella ELC) coolant. It would require a big investment of time and commitment in a fleet environment though. Flushing out one engine can take a full day, I can't see them dropping that kind of time into doing it the right way.
All 2005-2006 engines (not van model year, engine model year..it can be different) have the weak link in the High Pressure Oil System. The STC (snap to connect) fitting on the High Pressure Oil Pump (HPOP). It isn't a matter if it will fail, just when. It will give them no-starts when the truck is hot.
If they could get gauges on there and teach the drivers what to look for, that would save them a ton of headaches as well. At least the coolant temp and the oil temp. The drivers would be able to see that the 15° delta was being reached and report the problem before the EGR cooler splits. That would save a few sets of headgaskets.
If they run a full synthetic 5W40, that would quiet the engines down and the injectors like synthetic oil more than the "dinosaur" oil. The dino oils have varnishes that can collect within the injectors. When that happens the injector will stick and not operate properly when cold, a term was created to define this situation, it is called "stiction."
Synthetic oils do not have the varnishes in them, so the stiction issue goes away.
Thats about all I can think of off the top of my head right now.
The link in my sig "basic info" would help, but I seriously doubt a fleet is going to institute the changes.