According to this thread, Jose Luis Gonzalez in 1987 Euro cup beat Cram narrowly in 3:49 with a last lap of 49.9/50.0 with Cram just a couple tenths back, while Ryun was 50.6 (or 49 by one observer) in the 3:38 and also 50.6 at altitude in 1968 in Lake Tahoe in 3:49, plus Bashir and Cacho were about 50.6 in 1992.
http://trackandfieldnews.com/d...-1500-mile