The mint marks will be either P, S, or D, no other mint marks.The mint mark is located on reverse side of coin top center above Monticello, Jefferson's home. It would be most helpful for one to be able to see BOTH sides of the coin, rather than the front only. By the way, not all 1942 Jefferson Nickels are War Nickels! Just trying to help. Good luck with auction! Kindest regards!!