I was in the pawn shop and saw a Marlin rifle, but when I looked at the rifle to check the caliber, it read Cooper Arms, model 36. It is a 30-30 and it looks like miro-groove rifling. Can anyone give me some backgound on the rifle and the approximate value of the rifle in 85% condition.

The Cooper model 36 is a bolt gun. I think a good guess would be that someone rebarreled the Marlin with the Cooper barrel.