SP Condensed Freight Schedules early 1960s (my best guess) – this is a list that was compiled by author Dave Stanley. It does not include T&NO or SSW trains except those that operate on Southern Pacific proper. You can see a video interview with him here.
SP Through Manifest Merchandise Perishable Freight Schedule 24 10-15-1966
SP Freight Train Schedules 8-31-1972
SP Old and New Train Symbols 1-11-1974 A list of the original train names and new corresponding train symbols when SP converted to their alpha system.
SP Eugene Blocking Instructions 6-25-1975 Train schedules, bowl assignments, and blocking instructions for Eugene Yard
SP Condensed Perishable Merchandise Manifest 29 9-1-1977
SP System Blocking Book 3-31-1987 I don’t think this shows short distance manifest schedules, but it has blocking and schedules for intermodal and primary trains
SP Dallas and Austin 11 3-1-1938 – my token contribution to the massive collection at Wx4.org.
John Carr’s CarrTracks has extensive train symbol histories.
Wx4.org has a very large collection of employee timetables and much additional information as well.