At that time UP No. 6 was a unnamed mail and passenger train. Rode it once on a family vacation to LA/Disneyland in 1959
The correct train Name and number was City of Portland 106 east bound. I do remember train UP5/6 being listed as Mail and Express. I was a student at The University of Idaho 61-65 and frequently rode The City of Portland # 105/106 and the Portland Rose # 17/18 both ways.