This was in fact one of a group of six 33 rpm acetates from the Highway 61 Revisited recording sessions that seem to have surfaced at the same time. They mostly start with take announcements – and the odd bit of instruction – from Bob Johnston, sometimes a count-in from one of the musicians.  The endings are extended as on the Witmark “rough mix” tape, but usually even further, with Johnston breaking in again at the end, mostly just to say “OK”.  The extended openings and endings contain a few fragments of otherwise unheard backing music, but no Dylan vocals. 

The list of acetates is as follows:

1.      It Takes A Lot To Laugh, It Takes A Train To Cry

2.      Tombstone Blues  (without overdub)

3.      Positively 4^th Street

4.      Highway 61 Revisited

5.      Just Like Tom Thumb’s Blues

6.      Tombstone Blues  (with Chambers Brothers overdub)