Reply to "Head End Power Cars"

I used to see AMTRAK use baggage cars with a generator ( sounding loudly with a high pitch whine ) on the NE corridor in the mid/late 1970's - 80's when GG-1's were still in use.   These cars sometimes were directly behind a GG-1 or the last car within a passenger train consist.  They had louvers on each side of the car.    I'm pretty sure they didn't haul any baggage, only the generator to power lights, ac, and heating for the train.  As I would often take the train to Baltimore, I once asked a conductor about them.  That's when I learned about power cars.