should be 1973
according to a chart on the Browning website.
http://www.browning.com/services/dategun/detail.asp?id=13
From '68 to '76 Browning used the first two digits to indicate year of manufacture. However, something doesn't look right with the number you put down, the letter should be either an "G" or an "M" indicating whether it was a Light 12 or a Standard (magnum).
From the start of manufacture til the early -mid 50's they ran a straight serial number (all digits), then they changed to start with a letter (H, L, G, or M at different times) and then after '76 they switched systems again, to start with 5 digits then two letters indicating year (counting backwards with Z=1) and a 3 digit code for type of gun (light/magnum).
As far as value of the gun, it all depends on what condition it is in. I've seen decent A-5's for sale for anywhere between $300-$800, with most in the 400-500 range.
A lot of people say that the Belgian guns are worth more than the Japanese ones, and for a collector that might make sense. In my opinion, if the gun is to be used, a J. gun might be better. The B. guns should never be fired with steel shot, the barrels can score. A lot of the Jap. guns had choke tubes which weren't really in favor before then. If you wanted to change chokes before that, you either had to buy another barrel or add on a "dial-a-duck" (Poly-choke, Cutts, or Weaver were the biggest names but there were a couple of others also, ugly as sin to look at but they worked.)
I like A-5's. I've got two of them, my dad's '72 Light Twelve, and a '58 16 ga.
bergie