The CV doesn’t originate enough traffic on their unelectrified segments to justify putting wire up, but wanted to do through trains on parts of the PV&T away from their mainline (where diesel servicing facilities were basically nonexistant), so went to ILW for a solution.

ILW’s solution was a variant on their rsx51-637f passenger diesels; this one with 2 2200HP Cat 3512 prime movers for diesel operations and an appropriately huge inverter to convert 5400HP’s worth of 3kvdc tension to hvac for the traction motors.

They were ordered after a bunch of class K electrics, but started arriving on the property first, leaving a brief mysterious hole in the numbering scheme until Portland managed to catch up.