Those are the old Fp40s. They have a roll up door in the side. Amtrak uses them on push pull trains as it affords the crew a better form of protection than the end of a passenger car. The proper name is a Cab/baggage car but most of us call them cabbages. we see a lot of them here in the midwest. Another form of control car they used for awhile is the old Metroliner cars. originally built for the PRR but never put in service before Amtrak they are easily spotted (if still around) because of the mounting areas for the pantograph on the cab end.
The Long Island Railroad used old Alco FAs and later old F units, as control cabs. They basically deturboed the engine and used it to generate HEP, or more accurately, rear end power, on the west end of their trains. There were two reasons for this is. The first is that when they ran into the Long Island City Terminal they had no facilties to run the locomotives around the train nor the time to do so during the rush hours. Also, it allowed them to run non HEP equipped locomotives in passenger service. No baggage compartment though.