less than 100 to over 2000 USD depending on specifics.
Couple of thousand USD
Your Browning lightning superposed shotgun was made in the year 1968 with the serial number that you have provided.
100-1000 USD or so depending on specifics
It is one of the higher grades of wood in the stock and forearm.
100-1000 USD or more depending on specifics
You will need to call Browning.
Around $5000.
Impossible to tell without pictures.
I f you have a grade I superposed skeet? then it is going for 700 dollars if in 60% condition to 1200 dollars for one in 90% condition.If your browning is in 20ga. then you could add anywhere from 100-700 dollars depending on the amount of original finish left.
A. Marchal was a Master engraver with Browning Arms in the 50s/60s and engraved numerous Diana Grade Superposed Browning shotguns as well as high end Browning rifles.
Browning can tell you how it left the factory, and the gun can be dated by serial number.
Contact Browning or compare against known examples.