Peter, using the all RealTracks Jazz BeBop Quartet style, at 1:52 and 3:20 into song, the bass clearly plays a D Major line over the Eb Major chord. Now I am certainly familiar with superimposing a D Maj chord over an Eb bass note, but that would normally be initiated by the piano or guitar player so I am guessing this is not on purpose.

I have emailed the file to you as an MP3.