These 2 PS Smooth Side 56 Seat Diners were delivered to Union Pacific in mid '41 for use the "City of Los Angeles."  When built, the UP, C&NW, and SP had joint ownership of the cars.  They became the property of UP in '47 when the names "Biltmore" and "Ambassador" were given numbers CP 607 and CP 608.  In 56, the were renumbered 4817 and 4818.  Both were sold in '58.