One bearing surface has concave shape to threads
No other part numbers with same form, fit, and function found.
A nut, round in shape, having all or part of its outer surface knurled. It may have provisions for external wrenching. For items having a thickness (or height) exceeding two times the outside diameter, use post, electrical-mechanical equipment. See also nut (1), plain, round. (when height or thickness, and/or outside diameter is designated as a tolerance dimension, the maximum dimension will be used to determine compliance).
Classification: Nuts of iron or steel
NSN 6650-01-043-4221
NSN 6610-01-217-4162
NSN 2925-00-961-2117
NSN 6135-00-318-8359
NSN 5945-01-484-4542
NSN 6110-00-050-3730
NSN 6105-00-160-7804
NSN 5998-00-761-1105
NSN 5935-00-027-1341
NSN 5985-01-049-3692
NSN 5998-01-491-5559
NSN 5935-01-077-0035