Walter Sutton went to see William Carlos Williams at WCW's home in Rutherford, NJ, on October 11 and 20, and again on November 3 and 15. The recording, put together, is one hour and 59 minutes and a few seconds. The entire interview is now available in PENNsound. Here is the PENNsound Williams page. And here is the link directly to the mp3 file.
Sutton later edited American Free Verse: The Modern Revolution in Poetry.