I remember the first time I saw this piece. I wondered why some idiot had stripped the doors from a Pennsylvania Stock car to fix an AT&SF. I didn't buy it.
BIG MISTAKE!
Look at those doors again. They're slotted doors from a NYNH&H or PA boxcar. There are a handful of these around so if you find one, DON'T FIX IT!

Courtesy of Al Woodward