By 1966, the Southern wanted to discontinue most passenger services. The passenger "numbers" of all trains were closely watched and used for train-off petitions to the ICC and state PUCs. Here are two pages of passengers in "sleepers" for the first half of February, 1966. (Note: passenger counts are by Pullman "line number", not individual trains.)
Someone might look in the "Guides" and tell us which trains included these Pullman lines.