"Serial No. 30700157 (...)The generally accepted method of decoding Kenwood serial numbers is to subtract 2 from the first digit to get the year of manufacture, in your case 1991. The next two digits are the month, 07 being July. It's the 157th unit made that month. The earliest serial that I've personally seen on an 850 is 210xxxxx, October of 1990, although there may be some 209's around.