Sansui 9090DB dates??

hi all,
i recently acquired a Sansui 9090db. Can anyone tell me exactly when this model was released? The original owner claims it was purchased in 1970 HongKong, which does not jive with what I'd thought:that it is from a later (1976-1979) vintage. Anyone here know the straight dope?
I know mid-late 70's for sure, definitely not early 70's...
just found a few sites that say it came out in 1975
I actually owned this receiver it was sent to me by a serviceman stationed overseas. Believe it was around 1973, but don't know how long they had been out before I bought mine.
About 2 years.
According to the 9090DB was made from 1974-1979, the 9090 from 1977-1979