Seems to me that Paul used Panasonic SV3700 DAT decks to record the 2-track SBD feeds, then added the Tascam Hi-8-based DA-88 multitrack recorders around 1993. (I first remember seeing them in KC in August 1993)
When I started seeing Grateful Dead shows, Dan Healy used a pair of Panasonic SV3700's, as well as a high-quality professional 10-well cassette duplicator (I can't remember the brand, but it was a widely used system, though the GD's rig was the only time I ever saw it used in the field.) Starting around 1992 or 1993, they used the Alesis VHS-based ADAT multitrack recorders. Thinking back, I don't know if I ever saw the multitracks in the Dead's system before spring 1993 (Chapel Hill was the first time I recall noticing them)