A couple of foreign Canadian sisters, find themselves in the South with 3,203 feet of mixed freight and the task of bringing them north to Birmingham, AL hopefully without any delays. The combination of both SD75I units, the second CN #5668 tug at their consist with 8,600 horses. The "I" in the model name means "Isolated Cab". This design lowers noise and vibration for the crew during operation. Rubber separates the cab from the frame allowing a better ride.