OK Rogue12153, I did not do too good, but here is what I found in the "Book". The Model 66-1 looks like 1981, 19-2 was made between 1961-1966, could not find a KJF prefix in my book, and the 5906 was made between 1989-1999. I did not show a K prefix in my book for the 5906. Now if the K7108xx...