John,
  I have a lead here on a TF86-BX that I'd like to
take up
 but while the seller says it is indeed a TF86 (DSSI), the
 drive has labels on it that say TK86.
 My question is: are these in fact the same thing?
 I can't recall hearing of a TQK8x controller, in support
 of his claim. 
Yes, this is a DSSI drive.  There is a SCSI version of it, the
TZ86, which basically includes the SCSI-to-DSSI board.  I have
several TF85's of both types... very nice drives.  The 86's and
87's are higher capacity- I believe *but am unsure* that the
87 is SCSI-only.
--f