The M-K TE70-4S was a four-axle 2,800 hp (2.1 MW) B-B diesel-electric locomotive built by Morrison-Knudsen.

The four-stroke turbocharged engine was rated for a maximum of 3,240 hp (2.4 MW) at 1000 RPM.

The capability of the prime mover notwithstanding, the locomotive was rated at 2,800 hp (2.1 MW).

[3] The new prime mover required substantial alterations to the cab, carbody, and underframe.

[7] The locomotives carried a unique paint scheme featuring the red-and-orange of the SP's famed "Daylight" passenger trains, albeit in a different style.