Expander System Pivot Pin - Nut and Washer Type - Nord-Lock Group
Recessed Nuts, Recessed Pins and Industrial Pins
9/16" Tie Rod Castle Nut And Cotter Pin Kit - Broncograveyard.com
Steel Externally Threaded Taper Pin With Hex Nut, Plain Finish, Standard Tolerance, #4 Pin Size, 1/4"-28 Thread Size, 0.248" Large End Diameter, 0.232" Small End Diameter, 3/4" Length (Pack of 5): Amazon.com:
Wet Equalizer Bolt with Castle Nut, Grease Zerk and Cotter Pin - 3-1/2" Long Redline Trailer Leaf Spring Suspension 126A1
Castle Nuts - How to Install or Fit a Cotter Pin and Slotted Nut | Fasteners 101 - YouTube