SKB 5

HEY! I have a Ithaca-SKB 500 IN 20ga. 28" barrels I bought new in 1973. My first gun after graduating from H.S. in 72. Ser. # CF 569717. I ORDERED IT BUT WOULD LIKE TO FIND OUT WHEN IT WAS MADE 71, 72, 73? WHERE CAN I FIND THIS OUT? ALSO I DO NOT WANT TO REFINISH THE STOCK BUT SOME OF THE SHINE HAS WORN OFF THE WOOD AND I WOULD LIKE TO TRY AND BRING THIS BACK. I THINK IT IS JUST WHERE MY FACE HAS TOUCHED THE STOCK. I SHOOT OFF BOTH SHOLDERS SO IT IS ON BOTH SIDES. ANY IDEAS?
THANKS
TOMMY