According to the track listing, it closes out Disc 2:
10 Behind the Lines (Lyceum 80)
11 Duchess (Lyceum 80)
12 Guide Vocal (Lyceum 80)
13 Turn It On Again (Lyceum 80)
14 Duke's Travels (Lyceum 80)
15 Duke's End (Lyceum 80)
The Duke suite was originally conceived as a single piece of music, but they didn't want to do another "side-long epic" having already done that with Supper's Ready, largely because it would invite comparisons. So they split it up, opening and closing the album, with Turn It On Again opening what was originally Side Two of the LP. I had a friend who had a boot from the 1980 tour, and it started with a quick fade-up on Behind the Lines (I assumed it caught the bootlegger off guard) but otherwise was the entire suite. I wanted so badly to make a copy of it, but I didn't because I knew that every time I played it, I'd be annoyed all over again. Anyway, a legit release will be awesome even if I have a good quality boot.