As was pointed out, this is an M1028 with the M1010 charging system. From what I have been able to find out, they were a limited run of 1987 trucks that were specially ordered this way to provide the 200-amp capacity of the M1010 for the comm stuff. The A/C was sort of a a side-effect of how they were ordered/built. It could be hooked up to a shelter as shown above, but the heater controls are regular CUCV. The A/C had to be controlled from the unit in the shelter. It also has the fuel pump for the M1010 heater under the hood. The RPO sheet on this truck will show "seats - high back bucket" and "ambulance body", even though it doesn't have them. The VIN plate will have a GVW of 9450 and a curb weight of 7370 (the values for an M1010), but the NSN for an M1028.
This charging system didn't work right from the factory and was the subject of numerous PS articles. I'm not sure any truck that comes out will be working properly, although I have heard that if it was loaded enough, it would operate correctly. Otherwise, my best result (the truck in my avatar had this system) was to force one alternator to charge 14V and let the other do 24V by switching the orange and red wires on the DUVAC. Even then, it can be a flaky system.