From Chama to Durango the railroad had a rather up and down profile, with helpers typically used in both directions over parts of the line.
Westbound the line was mostly downhill from Chama to Arboles, and usually helpers would run light from Chama to Gato. Interestingly, except for a short climb from Willow Creek, the line was downhill from Chama to the Continental Divide near Azotea. Because of the climb out of Willow Creek, heavy trains would occasionally doublehead from Chama to Azotea with the helper running light from Azotea to Gato. Helpers would then be added at Gato for the climb to Falfa, and taken off at Falfa for the downhill run into Durango. Occasionally helpers would run light from Durango to Gato to help westbound trains.
Eastbound the tough part was the 2 percent climb from Carbon Junction to Falfa, with another 2 percent section through Monero canyon. Big eastbound trains usually operated with two engines doubleheaded through from Durango to Chama. But occasionally the helper would cut off at Falfa and drift back to Durango. And that could result in a real struggle through Monero canyon, or perhaps a helper would be sent from Chama to help from Lumberton.
Gato was a fairly busy spot with trains taking water, helpers coming on or off, and crews taking beans (lunch). Since by the 60's most traffic was to Farmington, loads were usually set out at Carbon Junction and eastbound empties picked up there, so trains between Carbon Junction and Durango were often short. But occasionally there were more cars than the siding would handle and the overflow would go into Durango with the Durango cars.