I found some relics in my collection. One is a timecard of Santa Fe trains operated under contract by Amtrak dating from 7-12-71.
Chicago-Los Angeles services was provided by trains #17 & 18. No train name.
The second timecard dates from 11-14-71. It covers former Santa Fe service. It refers to Chicago-Los Angeles service as trains #3 & 4 and by name---Super Chief/El Capitan.
Why the change in train #'s?
A third timecard dating from 6-11-72 essentially is the same as the 11-14-71 timecard except it shows the additional summer-only trains #19 and 20 on the Chicago-Los Angeles route. I rode #20 from L.A. to Albuquerque in August 1972.
I did not ride #3 until my grand Railpass circle trip of fall 1976.