Many of the mail trains on western roads carried eastern baggage cars loaded with magazines and news papers from the east. They were interchanged much as freight cars were but only on passenger/mail trains.
From the you tube video it appears that the Kato coupler (A unit rear coupler) appears to stick out too far. Thankfully, Kato kept the truck mounted coupler on the 'B' units and the rear of the 'A' units. Makes it easy to swap out the Kato coupler for 'T' shank Unimates for closer coupling.
I picked up some of these from Kato and they work as well as the Umimates but seem to be easier to couple. [FONT=verdana,arial,default][SIZE=-1]923090[/SIZE][/FONT]