Re: 1950's freight rules

David, there are others here who know far mre than I do about this, and I'm sure some of them will reply.
To begin with, as a general rule, steel framed cars, such as tank cars and 6500 flats were placed at the head end. This was done not only for the strength of the car itself, but also for the strength of the coupler pockets. Helpers were placed depending on specific restrictions in certain areas. West of Chama, two engines were often doubleheaded on the point. Between Chama and Cumbres, weight restrictions on Lobato Trestle prevented two large K-Class engines at the same time. If engines were doubled on the point, the helper had to cross light, followed by the road engine with the train. Often on this portion of the line, the helper was cut in ahead of the caboose, or about 10 cars back.
When pipe trains were switched and unloaded at Farmington, idlers were often seperated from the pipe gons and remained that way on the return trip where the trains were loaded and reassembled. Idlers were problematic and used less often as time went by and more long flats and gons could be rebuilt and made available. Bob Richardson used to comment that the entire right of way in the fifties was littered with broken and cast aside idlers.
I'm sure there will be other comments more informed than mine to follow.