Vintage WWll Era U.S. Navy Aircraft Navigation Aids 3 Pieces 1941 For Sale

One Dead Reckoning Computer AN-C-74-A Made by GFelsenthal & Sons ChicagoOne American Airlines Inc Navigational Computer Copyright 1941 Serial No A- 1408 For speed time and distance ( Turns but is stiff )One U.S. Navy Computer Mark 8 For air speed correction and altitude correction I have taken photos for your inspection, I am not a pilot and have no expertise in the area, if you have any questions, i will do the very best I can to answer. I can tell you that these items came from a lot that included ref. books and training materials that were all pilot related and WWll Era.