I have a 3rd gen cassette of this tape, labeled "Matrix 12/16/68 III" with the personnel listed as Garcia, Hart, Lesh, Harvey Mandel & George Chambers.
Side A contains about 42 minutees of music, listed on the label as follows: #Feel It Three O'Clock Blues Mojo Worker > jam Side B contains more than 45 minutes of music, listed as jam > Walkin the Water# Feel It cuts in after the beginning on my tape. The jam at the end of Side A comes to a conclusion. The jam labeled "Walkin The Water" cuts off very close to the end of my cassette while still in progress.