Isn't this one that's been turned into a control cab (& baggage car - note garage door on side) - engine removed. Somebody here on DA mentioned that some time ago...
Yeah, they're affectionately referred to as "cabbage" cars (cab+baggage). Outside of the Northeast Corridor, there aren't many Amfleet cars adapted to serve as the control unit for backwards running and so rather than scrap F40s completely as the P40/42 fleet came into their possession, Amtrak repurposed some because it was cheaper and faster than taking coaches out of service and doing renovations that would cost them seats they could sell to riders.