Torn up cars were not at all uncommon on the NG, especially on the roller coaster profile between Chama and Durango and the mixed load/empty status of the trains. If a train had a car with a a sticking triple valve that went into emergency at the wrong time, the slack action could be terrribly violent in a 70 car train. Johns pic of the box car is interesting as it takes a real hard yank to pull the drawbar out of a box car like that. Back in the "boxcar days" on the C&TS I had a dynamiter on a 28 car train that literally put the entire pasenger load on the floor. I felt certain we'd gotten a knuckle or a drawbar, as we stopped with a mighty bang and heavy jerk as the slack went out. But except for some skinned elbow, everything came out OK... Today we'd have 200 lawsuits from it.....