The drawing from Bachmann seems to show an early Budd Baggage, built in 1942, with unequal width baggage doors.
this car....
notice the corrugation all the way to the door openings...later Budd designs ended the corrugations a door's width from the opening; apparently the corrugations were being damaged by trucks or equipment backing into the cars. The very nice Kato Budd baggage (released as part of the "El Capitan" set reflects the look of one of these later Budd-built baggage cars.
If the Bachmann car is, indeed, an accurate rendition of this car, then I'll very much welcome a 'new' ATSF prototype head end car to the N scale market...definitely another car for the Fast Mail.
Bruce