We’ve already seen Milwaukee timetables from 1968 and 1970. Here’s one in between. Where the 1968 timetable showed trains 15 & 16, the former Olympian Hiawatha, cut back to Aberdeen, South Dakota, this one dropped it entirely.
The 1968 timetable also showed one fewer train a day between Chicago and Milwaukee (seven instead of eight). Otherwise, the two are pretty much the same.