File a police report anyway. Pawn shops are required to "hold" all the items they take in, and cops will search the "hold" rooms for property that's reported stolen. Who knows, your thief might be exceptionally stupid and not realize that.
I bet it was just an "opportunity" grab, and now somebody has a nice new box in their garage.
I NEVER, EVER leave stuff in the bed of my truck whenever possible. If it's small enough I put in the cab, or I will drive home and drop it off before parking it anywhere in public. Had a $1k mountain bike stolen (it was locked to the bed anchor, they cut it) from my campus parking lot.