Here is a mint condition Lie Nielsen butt mortise plane.    The plane comes complete with box and instructions.   The only signs of use I see are the blade was lightly honed.   From the LN web site:

No. 40B Butt Mortise Plane

Our Butt Mortise Plane will help you cut neat, precise mortises for hinges, lock fronts, and strike plates in a fraction of the time it takes to set up an electric router and template.

Based on an original 1948 design by W. A. Dohmeyer, this tool does a job no other plane can do. The elongated slot in front of the blade provides a clear view of the work. It is easy to use to make precise mortises with sharply square corners to an accurate, uniform depth. Useful for mortising dutchmen to repair flaws in jambs, furniture, and doors.

  • 9-5/8" long x 1-1/2" wide.
  • Blade is .875" wide by .115" thick, A2 Tool Steel.
  • Iron body, 1.70 lbs.