Amtrak #3, the westbound Southwest Chief, was running very, very late on Friday, December 28th, 2012. So late that the equipment had not yet arrived in Los Angeles before #4, the eastbound Southwest Chief, was due to depart. (The equipment that arrives in the morning on #3 is serviced and then becomes that evening's #4.) Fortunately, the equipment from the Sunset Limited was available, and so #4 that evening had equipment intended for the Sunset - including one of Amtrak's Heritage diesels: P42DC 184 in the Phase IV scheme. And it was on the point!