5310-00-017-8397 (178397)
NSN 5310-00-017-8397 (NIIN 00-017-8397) is a lock washer in Federal Supply Class 5310, Nuts And Washers — a washer, usually round, with a centrally-located hole. Manufacturer part number 178397 (General Motors LLC, CAGE 7X677); also referenced as 712122 (Chrysler Realty Company LLC); 87497C (Brockway Motor Trucks Div Of Mack).
Key specs: 40 to 50 rockwell c hardness; full characteristics table below. NIIN assigned January 1963; DEMIL A (none required). Related NSN 5310-00-395-2948.