Hex nut is 0.38-16 unc-2b fit
A headed externally threaded fastener whose threaded portion is of one nominal diameter with an elliptical neck, directly beneath the head.
NSN 5855-01-466-5353
NSN 5996-01-398-0037
NSN 6145-00-090-5411
NSN 2925-01-043-9786
NSN 6320-01-415-0953
NSN 2925-00-142-9919
NSN 6685-01-128-2519
NSN 5835-01-245-8077
NSN 6110-00-244-2308
NSN 5930-01-160-8539
NSN 4140-00-413-0877
NSN 5950-01-205-2757