Hi Pete, those stamped alpha numeric numbers were all I found. Here's a link to a 1000 on ebay with several really good pics of the back side of the receiver showing a stamp of S F 6198.Hi tech507, welcome to AudioKarma Exclusively Sansui! Thanks for the serial numbers. Can you take another look at the 1000, there shouldn't be any alpha characters in a Sansui serial number and it should have either 8 or 9 digits total. Thanks.
- Pete