This is the closest I've been able to figure it out.
year/month
(I didn't use the AK data base - this is independent research.)
AU/TU-XXX models and dates
AU-111 1966
AU-101 Date unknown.........or 1973-75
AU-505 Date unknown (1973?)
TU-505 Date unknown.........or 1973-75
AU-222 1968
AU-777 1967/5
TU-777 1968/3...................or 1967-70
AU-777A 1970......................or 1969
AU-555 1968/5...................or 1970-73
TU-555 1968/6
AU-222 1968/6...................or 1970-74
AU-777D 1969/6...................or 1970-73
AU-333 ? (was there one?)......? 1970-74
AU-555A 1970......................or 1971-75
AU-999 1970/2...................1970-1973
TU-999 1970......................1970-1972
AU-666 1970/5...................1971-1973
TU-666 1970/6...................or 1971-1973
AU-888 1971
TU-888 1971
In answer to one question from the OP - There was supposedly an AU-333 model. This I base upon sites such as "The Best of Sansui". I think this is one model from the Sui line (1967-1970) that should be considered rare indeed. Also from my limited "While traveling" the net I was surprised that there was a Sansui AU-117.
I don't know about the AU-333 either. It's a mystery. I've seen it 'mentioned' once or twice before, and yes...on 'Best of Sansui', but never have seen a photo of one. If it does exist...it's beyond super rare. If it exists, I would of seen a photo by now. I don't think it exists, but...who knows? A Sansui mystery!
AU-117: It would take me a while to find it in my notes. I could find it if you really want the date and data on the amp.
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And just in case you ever wondered about the alpha dates and designations (while I had my external hard drive out):
1986 AU-a607 (straight number - no suffix)
1987 AU-a607 i
1988 AU-a607 EXTRA
1989 DG
1989 AU-a607 L EXTRA
1990 AU-a607 DR
1991 R
1991 AU-a607 MOS PREMIUM
1992 AU-a607 KX
1993 AU-a607 XR
1994 K
1995 AU-a607 MR (domestic), MRX (international)
1997 AU-a607 NRA
1997 RX
1998 MRV
1999 AU-a607 NRA II