I needed a lockable hitch pin for my camper.

Problem is it's a half inch pin and even the extra long ones weren't quite long enough to lock, let alone allow for use of the safety cotter pin.  So I just used a drill and me bench grinder to cut down some of the hurled section and effectively extend the length of it so that it would work.  I little spray paint and it almost looks factory.  The hurling used to be about twice as long as it is now in the pictures below.

PSA: If you use a locking hitch pin, you should ALSO use the cotter pin hole.  The locks are tamper resistant, but not necessarily good at staying on through the forces of towing a trailer.  If it pops off, you want a backup.  On top of that, the cotter pin keeps the forces from being applied to the lock in the fist place!