These 15 ACF Smooth Side Dome Observation Bar Lounge cars were delivered to Union Pacific in early '55 for use on the "City of LA/Portland" and the "Challenger."   After 2 months on the "Challenger," they were reassigned to the "City of St. Louis," running between Kansas City and LA. They were numbered 9000 to 9014.  All had a diaphragm added in '56 for mid-train operation.  All were sold to the original Auto Train in '73.