Product Description
9/16" -18 lock nut is generally used on hangers or attaching bolts.
Lock nuts can damage the thread on some u-bolts made out of a softer material.
Nut, .5625 -18, Hex, top, Lock. 4101-6.
For Shackle Bolt, 9/16-18 Top Lock Thread. Same As Dexter 006-007-00, Redneck 916DLN, Nuera 27-004, Quality 4101-6.