Jennings, Stember, and Lunn were very good runners, but they were not in the same category as today's top American 1500 meter runners. With 3:35+ top-end speed they did what you would expected them to do. In 2000 (get this) Jason Pryah actually made the Olympic finals with only a 3:36 1500 PR.
Before Webb and Lagat started winning respect for US milers, it was David Krummenacker that was essentially carrying US middle distance running on his shoulders. Before Webb, Krummenacker had the fastest 1500 and 800 meter combination speed of any US miler.
Last I heard, Krummenacker was being used as a rabbit, which probably means he still has(had) at least 1:45 800meter speed.
Krummenacker has been quoted as saying he hated running the 1500 despite having a 3:31 pr in that event.
Quote of the day (from the not so distance past).
" A 3:30 guy will beat a 3:35 guy everytime"
- Steve Holman (3:31+, 3:50 mile)